U.S. patent application number 17/358024 was filed with the patent office on 2022-03-24 for organic single-crystalline semiconductor structure and preparation method thereof.
The applicant listed for this patent is ZHEJIANG UNIVERSITY. Invention is credited to Hanying Li, Ruihan Wu.
Application Number | 20220093884 17/358024 |
Document ID | / |
Family ID | 1000006050045 |
Filed Date | 2022-03-24 |
United States Patent
Application |
20220093884 |
Kind Code |
A1 |
Li; Hanying ; et
al. |
March 24, 2022 |
ORGANIC SINGLE-CRYSTALLINE SEMICONDUCTOR STRUCTURE AND PREPARATION
METHOD THEREOF
Abstract
An organic single-crystalline semiconductor structure is
provided. The organic single-crystalline semiconductor structure
composes substrate, growth-assisted layer, electrodes, organic
single-crystalline semiconductor layer. The growth-assisted layer
deposited on the substrate from bottom to top. The organic
single-crystalline semiconductor layer is defined as the organic
semiconductor single-crystal thin film which basically maintained
its original morphology after crossing the electrodes. The organic
single-crystalline semiconductor thin film could realize
full-covering over the arbitrary-shaped or arbitrary-sized
bottom-contacted substrates, and the nearly ideal morphology on
industrialized scale could be achieved. This organic
single-crystalline semiconductor structure could be applied as key
part in organic field-effect transistor, in order to realized fast
transportation of charge carriers. A facially manufactured and high
performance organic field-effect transistor device is also
provided, with good potential in the fields of organic electronics
and optoelectronics.
Inventors: |
Li; Hanying; (Hangzhou,
CN) ; Wu; Ruihan; (Hangzhou, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZHEJIANG UNIVERSITY |
Hangzhou |
|
CN |
|
|
Family ID: |
1000006050045 |
Appl. No.: |
17/358024 |
Filed: |
June 25, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/CN2020/112727 |
Aug 31, 2020 |
|
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17358024 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 51/0541 20130101;
H01L 51/0007 20130101; H01L 51/0545 20130101 |
International
Class: |
H01L 51/05 20060101
H01L051/05; H01L 51/00 20060101 H01L051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2019 |
CN |
201910810780.9 |
Nov 3, 2019 |
CN |
201911062819.X |
Mar 12, 2020 |
CN |
202010172053.7 |
Claims
1. An organic single-crystalline semiconductor structure,
comprising a substrate, a growth-assistant layer, electrodes and an
organic single-crystalline semiconductor layer; wherein the last
three are deposited sequentially from bottom to top on the
substrate; the organic single crystal semiconductor layer is grown
on the growth-assistant layer and the electrodes, the organic
semiconductor layer is composed of organic single-crystalline
semiconductor thin film, and the organic single-crystalline
semiconductor thin film is constructed by organic semiconductor
single crystal arrays; the morphology of organic semiconductor
single crystal array keeps basically unchanged before crossing the
electrode (100), at the electrode edges (101 and 103), on the
electrode (102), and after crossing the electrode (104).
2. The organic single-crystalline semiconductor structure of claim
1, wherein he organic single-crystalline semiconductor thin film
can realize complete/full coverage on a substrate of arbitrary
shape or arbitrary size.
3. The organic single-crystalline semiconductor structure of claim
1, wherein the organic single-crystalline semiconductor thin films
have an effective coverage ratio f.sub.cr.gtoreq.80% in the
lengthwise direction of the crystals, and an effective coverage
ratio f.sub.cp.gtoreq.50% in the vertical direction of the
crystals.
4. The organic single-crystalline semiconductor structure of claim
3, wherein the lengthwise directional effective coverage ratio
f.sub.cr=(c.sub.L1+c.sub.L2+ . . . +c.sub.Lm)/(L.sub.1+L.sub.2+ . .
. +L.sub.m), wherein m is a positive integer greater than or equal
to 5, c.sub.L1, c.sub.L2, . . . , c.sub.Lm represent continuous
lengths of crystals c.sub.L in the 1, 2, . . . , m channels in m
adjacent and continuous channels, respectively; and L.sub.1,
L.sub.2, . . . , L.sub.m represent the lengths L of the 1, 2, . . .
, m channels covered by crystals, respectively; for the vertical
directional effective coverage ratio, fcp=(k.sub.1+k.sub.2+ . . .
+k.sub.n)/W, k.sub.1, k.sub.2, . . . , k.sub.n represent the
contact widths k between the 1, 2, . . . , n crystals and
source/drain electrodes, respectively, W represents width of
channel, wherein n is a positive integer greater than or equal to
8.
5. The organic single-crystalline semiconductor structure of claim
1, wherein the electrodes contact with the growth-assistant layer
with protruding outside of the growth-assistant layer; the
electrodes are in contact with the growth-assistant layer in an
upper type and/or embedded type, the upper type refers to the upper
surface of growth-assistant layer in contact with the lower surface
of the electrodes, and the embedded type refers to the electrodes
half-embedding or penetrating the growth-assistant layer.
6. The organic single-crystalline semiconductor structure of claim
1, wherein the organic single-crystalline semiconductor thin films
are well-aligned organic semiconductor single crystal arrays, which
is composed of multiple separate and independent linear-type
elements; the multiple linear elements are arranged in a
linear-type arrangement, and the linear-type arrangement refers to
the well-aligned orientation/arrangement of the linear elements
along the crystal growth direction; the morphology of linear
elements keep basically unchanged before crossing the electrode
(100), at the electrode edges (101 and 103), on the electrode
(102), and after crossing the electrode (104); the linear element
is an independent crystal with single-crystalline morphology.
7. The organic single-crystalline semiconductor structure of claim
6, wherein the well-aligned orientation/arrangement refers to the
degree of orientation F.gtoreq.0.625.
8. The organic single-crystalline semiconductor structure of claim
7, wherein the detection method of F is: randomly selecting n
linear elements of the organic single-crystalline semiconductor
thin film as samples, wherein n is a positive integer greater than
or equal to 10; the crystal growth direction is taken as the
reference direction; take the angle between the direction of the
longest dimension c of each linear element and the reference
direction as the orientation angle A, the average value of the
orientation angles of the n linear elements as ; the degree of
orientation F=0.5*(3*cos.sup.2 -1).
9. The organic single-crystalline semiconductor structure of claim
6, wherein the morphology of the linear element is pseudo
one-dimensional (pseudo 1D, p1D) or pseudo two-dimensional (pseudo
2D, p2D); when the length c of a single crystal along the crystal
growth direction is much larger than the width a of the crystal and
the thickness b of the crystal, that is, when c/a.gtoreq.500 and
c/b.gtoreq.500, the morphology is p1D.
10. The organic single-crystalline semiconductor structure of claim
6, wherein the top view of linear element is linear or facial form
in the stereogram, and the thickness b of linear element is 2 nm to
400 nm.
11. The organic single-crystalline semiconductor structure of claim
6, wherein the thickness of linear element is highly uniform.
12. The organic single-crystalline semiconductor structure of claim
6, wherein the detection method of "the thickness of linear element
is highly uniform" is: randomly taking p samples of linear elements
in the organic single-crystalline semiconductor thin film and
characterizing the thickness b of the linear elements, the average
thickness of p linear elements is b, and p is a positive integer
greater than or equal to 8, when b<10 nm, the coefficient of
variation of the thickness of the linear element in p samples is
.ltoreq.40%, when 10 nm.ltoreq.b.ltoreq.50 nm, the coefficient of
variation of the thickness of the linear element in p samples is
.ltoreq.30%, when b.gtoreq.50 nm, the coefficient of variation of
the thickness of the linear element in p samples is .ltoreq.20%,
indicating that linear elements have highly uniform thickness;
preferably, when b<10 nm, the coefficient of variation of the
thickness of the linear element in p samples is .ltoreq.30%, when
10 nm.ltoreq.b.ltoreq.50 nm, the coefficient of variation of the
thickness of the linear element in p samples is .ltoreq.20%, when
b.gtoreq.50 nm, the coefficient of variation of the thickness of
the linear element in p samples is .ltoreq.10%.
13. The organic single-crystalline semiconductor structure of claim
6, wherein the gap width g of each of the linear elements along the
crystal growth direction is 0 mm to 1 mm; preferably, the gap width
g.ltoreq.10 .mu.m.
14. The organic single-crystalline semiconductor structure of claim
1, wherein the growth-assistant layer is an organic insulating thin
film.
15. The organic single-crystalline semiconductor structure of claim
14, wherein the water contact angle CA.sub.water that between the
organic insulating thin film and water is 30.degree. to
120.degree..
16. The organic single-crystalline semiconductor structure of claim
14, wherein the material of the organic insulating film has
.pi.-conjugated system, and the .pi.-conjugated system refers to a
system wherein conjugated .pi. bonds are able to form.
17. The organic single-crystalline semiconductor structure of claim
14, wherein the material of organic insulating film is selected
from any one or more from the group consisting of self-assembled
small molecules containing silyl groups, self-assembled small
molecules containing phosphate groups, self-assembled small
molecules containing thiol groups, dielectric polymers.
18. The organic single-crystalline semiconductor structure of claim
1, wherein the core of the material of the organic
single-crystalline semiconductor thin film contains a conjugated
structure, with a band gap width .ltoreq.3.5 eV.
19. The organic single-crystalline semiconductor structure of claim
1, wherein the organic semiconductor single crystal array is
obtained by in-situ uniform growth crossing the electrodes.
20. A field-effect transistor, comprising: the organic
single-crystalline semiconductor structure of claim 1; the
field-effect transistor includes top-gate and bottom-gate devices;
the gate and dielectric layer of the top-gate devices are located
above the organic single-crystalline semiconductor structure; the
gate and dielectric layer of the bottom-gate devices are located
beneath the organic single-crystalline semiconductor structure.
21. A preparation method of the organic single-crystalline
semiconductor structure, comprising: (1) sequentially preparing the
growth-assistant layer and the electrodes on the substrate;
preferably, the electrodes are in contact with the growth-assistant
layer in an upper type and/or embedded type; the upper type means
that the upper surface of the growth-assistant layer is in contact
with the lower surface of the electrodes, and the embedded type
means that the electrode is half-embed or penetrates the
growth-assistant layer; (2) dissolving the organic semiconductor
material in an organic solvent to prepare an organic semiconductor
solution; (3) regulating the temperature and humidity of the growth
environment to obtain a stable growth environment, the deviation of
the ambient temperature is .ltoreq..+-.2.degree. C., and the
deviation of the ambient humidity is .ltoreq..+-.3%; (4) adjusting
the gap distance between the shearing tool and the substrate that
prepared in step (1), the gap distance is 50 .mu.m to 300 .mu.m;
guaranteeing the deviation of the gap distance that between the
lower surface of the shearing tool and the substrate .ltoreq.10
.mu.m in order to obtain a stable storage space for solution; the
solution storage space is the space formed between the lower
surface of the shearing tool and the substrate; (5) filling the
organic semiconductor solution prepared in step (2) into the
solution storage space prepared in step (4), and let it stand for 1
to 30 seconds after the filling is completed; (6) shearing the
organic semiconductor solution at a constant linear velocity under
a constant shearing temperature in a constant direction from (100)
to (104) to achieve organic single-crystalline semiconductor thin
film on the substrates, wherein (100) represents before crossing
the electrodes and (104) represents after crossing the electrodes;
the organic single-crystalline semiconductor thin film is composed
of organic semiconductor single crystal arrays, and the morphology
of organic semiconductor single crystal array keeps basically
unchanged before crossing the electrode (100), at the electrode
edges (101 and 103), on the electrode (102), and after crossing the
electrode (104); the constant shearing temperature refers to the
temperature deviation .ltoreq..+-.1.degree. C. in the space
including the substrate and the solution storage space; the
constant linear velocity refers to the deviation of the linear
velocity .ltoreq..+-.20 .mu.m/s.
22. The preparation method of claim 21, wherein the step of further
treatment for the organic single-crystalline semiconductor thin
films after step (6) are also included.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT Patent Application
No. PCT/CN2020/112727, filed on Aug. 31, 2020, entitled "ORGANIC
SINGLE-CRYSTALLINE SEMICONDUCTOR STRUCTURE AND PREPARATION METHOD
THEREOF", which claims foreign priority of Chinese Patent
Applications Nos. 201910810780.9 filed Aug. 29, 2019;
201911062819.X, filed Nov. 3, 2019; 202010172053.7, filed Mar. 12,
2020 in the China National Intellectual Property Administration
(CNIPA), the entire contents of which are hereby incorporated by
reference in their entireties.
TECHNICAL FIELD
[0002] The disclosure relates to the technical field of organic
semiconductors, and particularly relates to an organic
single-crystalline semiconductor structure and preparation method
thereof.
BACKGROUND
[0003] In the field of semiconductor devices, organic semiconductor
devices have drawn attention in a wide range due to the
lightweight, flexibility, as well as potential of mass production.
Enormous new techniques have dramatically increased the development
of organic optoelectronic devices including organic photovoltaics
(OPVs), organic light-emitting diodes (OLEDs), and organic
field-effect transistors (OFETs). The device structure is one of
the keys to realize high-performance optoelectronic functions. For
instance, the structure of OFET mainly comprises: (i) electrodes,
which could be classified to source, drain and gate according to
the different function; (ii) organic semiconductor layer; which is
the most essential part as active layer; (iii) dielectric
layer/insulating layer.
[0004] Currently, BGTC (BGTC, FIG. 1A), Bottom Gate-Bottom Contact
(BGBC, FIG. 1B), and TGBC (TGBC, FIG. 1C) are common device
configurations used for OFETs (J. Zaumseil et al., Chemical
Reviews, 107, 4, 1296(2007)). The major differences are on the
basis of the relative position to each other among source/drain
electrodes, organic semiconductor layer and gate electrodes. The
source and drain electrodes are usually located at the same side
relative to the organic semiconductor layer, thus the source/drain
electrodes are used as a general term for the source electrode and
the drain electrode.
[0005] According to the working principle of OFETs, charge carriers
are injected from the source and extracted by drain. The charge
accumulation zone are formed at the interface between the organic
semiconductor layer and the dielectric layer to construct the
conduction pathways. As illustrated in FIG. 2 (A. Fischer et al.,
Physics Review Applied 8, 054012(2017)), the source/drain
electrodes of the coplanar devices (e.g. BGBC) are located at the
same side with dielectric layer in relation to organic
semiconductor layer. In this situation, the injection of charge
carriers occurs at the contact edges between the source and the
organic semiconductor layer. Moreover, depletion regions are formed
between the contact edges and conduction pathways formed by the
accumulated charges. The effective transport length of charge
carriers is reduced, and it becomes to a bottleneck for charge
carriers' injection and extraction.
[0006] With respect to staggered devices including BGTC and TGBC,
all the contact area (which is between source/drain electrodes and
organic semiconductor layer) facing the gate electrodes can be
involved in the injection and extraction of charge carriers; the
current is not 0; moreover, better device performance could be
achieved with a larger the injection area from the source
electrodes, reduced contact resistances, as well as larger active
regions. In particular, during the fabrication process of BGTC
devices (FIG. 1A), the semiconductor layer is deposited on the gate
dielectric, and source/drain electrodes are deposited at last. This
device architecture is widely used in organic semiconductor
thin-film field-effect transistors. However, the thermal damage on
the organic semiconductor layer are inevitable when depositing
source/drain electrodes. The thermal damage refers to a reduced
output current which is induced by non-uniformly distributed
density of trap states around the source/drain electrodes.
Furthermore, metal atoms especially Au or Ag might penetrate into
the organic semiconductor thin-film to change the barrier at the
electrode/semiconductor contact interface, resulting in great
affection on the injection of charge carriers. Moreover, since the
organic semiconductor layer of BGTC devices is directly exposed to
the air, the device lifetime is easily affected by the environment,
therefore the stability problems of device should be
considered.
[0007] In TGBC devices (FIG. 1C), the organic semiconductor layer
is located on the top of source/drain electrodes. Due to the
gravity force, the contact area between organic semiconductor layer
and source/drain electrodes are larger than that in Top Contact
devices, which is better for realizing efficient injection of
charge carriers. The electrical performance of organic
semiconductor devices is also restricted by resistance, contact
resistance problems are considered to limit the transit frequencies
for OFETs. Higher contact resistance requires higher voltage for
device operation, and it also lead to thermal instability of
devices. Especially for short-channel devices in integrated
circuits, the ratio of depletion region under source/drain
electrodes to the entire channel gets larger with shorter channel,
and it also contributes a larger ratio of contact resistance to the
total resistance, eventually the device performance could be
severely hampered. To lower the contact resistance, suppressing the
contribution of metal/organic interface resistance (R.sub.int) and
access resistance (R.sub.access) is wildly adopted. It has been
reported that contact resistance could be significantly reduced by
introducing appropriate dopant layer between source/drain
electrodes and organic semiconductor layer and adopting TGBC
configuration instead of BGTC, respectively. (P. Darmawan et al.,
Advanced Functional Materials, 22, 4577 (2012)) As it showed in
FIG. 3, the total resistance of BGTC devices is consist of
R.sub.int, R.sub.access and channel resistance (R.sub.channel). As
for TGBC devices, due to the overlapping organic layer on top of
the source/drain electrodes, the access region (for
charge-transport process in the bulk of the semiconductor from the
contact to the channel) has been reduced, thus the total resistance
only consists of R.sub.int and R.sub.channel, and the limit of
R.sub.access steamed from thickness of bulk organic semiconductor
layer has been get rid of, furthermore, contact resistance has been
significantly lowered (the contact resistance of the BGTC devices
can be significantly reduced from 200 k.OMEGA. cm to 1.8 k.OMEGA.
cm in TGBC devices). During the preparation of bottom contact
devices, the source/drain electrodes are pre-deposited on the
substrate. In one hand, the damage on the organic semiconductor
layer from source/drain evaporation process could be avoided. In
another hand, devices with high accuracy could be fabricated by
employing the conventional lithography techniques applied in
inorganic micro-electronics, in this way, the device integration
could be improved. (M. Mas-Torrent et al., Chemical Reviews, 2011,
111, 4833 (2011)). To enhance the device performance, selective
modification at the contact between organic semiconductor layer and
source/drain electrodes is usually required, for bottom contact
devices, the highly selective patterned modification on the
electrodes could be realized without destroying the organic
semiconductor layer. Moreover, the modification methods are more
variable than those for top contact devices, including solution
dipping method, vapor deposition method and evaporation method.
Besides, since the organic semiconductor layer located beneath the
dielectric layer, the active layer is protected by dielectric
layer, the stability of semiconductor devices could be improved as
well as tolerance to water/oxygen, which is beneficial for
application in actual production and daily use.
[0008] The performance of organic semiconductor is dependent of
organic semiconductor materials, morphology of organic
semiconductor layer, effective coverage ratio and the synergistic
integration of three factors aforementioned with device structures.
Changing any of these factors will have a significant impact on
device performance (C. Reese et al., Materials Today, 10, 3(2007)).
Organic semiconductor layer is a key role as active layer in
realizing electrical/optoelectrical performance. According to the
ordering of molecular packing in the structure of materials, from
low to high, organic semiconductor layer usually exists as
amorphous, polycrystalline or single-crystallin states. The
highly-ordered organic semiconductor layer has been proved to be an
efficient way to obtain high performance semiconductor devices,
since the carrier mobility and excitons diffusion length are
strongly dependent of ordering of molecular packing. Carrier
mobility is also termed as mobility. For field-effect transistors,
the performance mainly depends on mobility, threshold voltage and
on/off ratio. In particular, mobility is a key parameter for device
performance, mobility .mu. (cm.sup.2 V.sup.-1 s.sup.-1) refers to
the proportionality constant between the magnitude of an applied
electric field and the velocity it imparts on a charge carrier.
[0009] For a same material, organic single crystal has highly
ordered structure, no boundaries and less defects compared with its
amorphous or polycrystalline counterparts. It leads to a superior
charge carrier mobility in organic single crystals, which is
favorable in thin-film semiconductor devices for charge transport.
Furthermore, high mobility organic semiconductor devices could be
easily obtained. For example, the devices based on amorphous or
polycrystalline rubrene have mobilities around 10.sup.-3-10.sup.-4
cm.sup.2 V.sup.-1 s.sup.-1. However, the highest mobility of
single-crystalline rubrene semiconductor devices is about 40
cm.sup.2 V.sup.-1 s.sup.-1. It's easy to find the mobility
exhibited is nearly 5 orders of magnitude higher than those in
amorphous or polycrystalline counterparts, and faster operation
speed of organic devices is achieved. (J. Takeya et al., Applied
Physics Letters 90, 102120 (2007)).
[0010] In order to maintain the morphology perfection of organic
semiconductor layer, the morphology is supposed to remain basically
unchanged during growth. Especially for organic single-crystalline
semiconductor layer based on organic semiconductor single-crystal
thin film, if the morphology has changed or deformed, the defects
will be introduced. Eventually, the charge transport could be
severely impeded by defects and the performance of organic
semiconductor devices might be suppressed.
[0011] Similarly, the effective coverage ratio fc of organic
semiconductor layer plays an essential part in achieving high
performance organic semiconductor devices. The fc is defined as the
ratio of the effective area to total area in the channel of organic
semiconductor devices, notably, the effective area is continuous
along the channel direction. For example, in single-crystalline
organic semiconductor devices, the organic semiconductor layer is
composed of single-crystal thin film from organic semiconductor.
The single-crystal thin film of organic semiconductor is comprised
of multiple crystals, which are existed as single-crystalline
states. The effective coverage ratio could be divided into two
dimensions, one is lengthwise direction (which is parallel to the
growth direction of crystals) and the other is vertical direction
(which is perpendicular to the growth direction of crystals). The
lengthwise directional effective coverage ratio f.sub.cr refers to
the ratio of the continuous length of crystals in multiple channels
to total length of channels. The f.sub.cr reflected the
contribution of organic single-crystalline semiconductor thin film
to the substrate at the crystal growth direction. The vertical
directional effective coverage ratio f.sub.cp refers to the ratio
of the sum of crystal widths in the designated channel to the
channel width. The f.sub.cp reflected the contribution of the sum
of crystal widths to the substrate at a direction which is
perpendicular to the crystal growth. As FIG. 5 illustrated, for the
lengthwise directional effective coverage ratio,
f.sub.cr=(c.sub.L1+c.sub.L2+ . . . +c.sub.Lm)/(L.sub.1+L.sub.2+ . .
. +L.sub.m), m is a positive integer greater than or equal to 5,
c.sub.L1, c.sub.L2, . . . , c.sub.Lm represent continuous lengths
of crystals c.sub.L in the 1, 2, . . . , m channels in m adjacent
and continuous channels, respectively. And L1, L2, . . . , Lm
represent the lengths L of the 1, 2, . . . , m channels covered by
crystals, respectively. For The vertical directional effective
coverage ratio, f.sub.cp=(k.sub.1+k.sub.2+ . . . +k.sub.n)/W,
k.sub.1, k.sub.2, . . . , k.sub.n represent the contact widths k
between the 1, 2, . . . , n crystals and source/drain electrodes,
respectively; W represents width of channel, n is a positive
integer greater than or equal to 8. Higher f.sub.cr is obtained
with better the continuity of crystals. In a channel with same
length, larger contact length (k) between crystal and source/drain
electrodes results in smaller gap width (g). The width of actual
transport pathway for charge carriers gets larger with higher
f.sub.cp, and better performance of semiconductor devices could be
realized. When gap width (g)=0, the f.sub.cp could achieve 100%.
Ideally, for organic single-crystalline semiconductor thin films,
it is necessary to achieve a sufficiently high effective coverage
in both the lengthwise direction and the vertical direction. That
is, the organic single-crystalline semiconductor thin films are
required to be able to achieve complete/full coverage on a
substrate of arbitrary shape or arbitrary size. The complete/full
coverage could be defined as f.sub.cr.gtoreq.80% and
f.sub.cp.gtoreq.50% in organic single-crystalline semiconductor
thin films. However, the complete/full coverage cannot be realized
with current technology.
[0012] In summary, the ideal industrialized organic semiconductor
devices have 4 requirements as follows: 1) the device configuration
is bottom contact structure; 2) the organic semiconductor layer is
single-crystalline; 3) the morphology of organic semiconductor
layer is single-crystal thin film of organic semiconductor with
uniform growth; 4) the aforementioned organic single-crystalline
semiconductor thin film has effective coverage as large as
possible, and it is best to achieve complete/full coverage on a
substrate of arbitrary shape or arbitrary size. Better
electrical/optoelectrical performance could be obtained if the 4
requirements above-mentioned are fulfilled. Furthermore, the high
integration of multiple device arrays on a same organic
single-crystalline semiconductor thin film should be realized.
However, since the molecules in organic semiconductor single
crystals are required to be arranged regularly and periodically in
three-dimensional space, thus, the growth of organic semiconductor
single crystals are more difficult compared with their
polycrystalline or amorphous counterparts. Extraordinary control is
needed for regulation on the morphology of single crystals, and it
is extremely difficult to achieve. (M. Niazi et al., Advanced
Functional Materials, 26, 2371 (2016)). Using current technology
cannot realize complete/full coverage of organic single-crystalline
semiconductor thin film in bottom contact structure in laboratory
or factory.
[0013] In the past, large-size/large-area/large-scale organic
single-crystalline semiconductor thin films with controllable
morphology have been reported. For example, organic semiconductor
single crystals could be prepared up to several hundreds of
micrometers in length by utilizing drop-casting, spin-coating,
printing, meniscus-guided coating and so on. (S. S. Lee et al.,
Advanced Materials, 21, 3605 (2009); H. Li et al., Advanced
Materials, 24, 2588 (2012); H. Minemawari et al., Nature, 475,
364(2011)). It is wildly known that the surface roughness of growth
interface will affect the molecular packing, resulting in
morphology change of organic semiconductor crystals as well as
non-uniformly growth. (W. Shao et al., Chemical Science, 2,
590(2011)). The growth interface refers to the contact interface
where organic semiconductor molecules grow. According to the
different device configuration, the growth interface of bottom
contact devices is the contact interface between organic
semiconductor layer and substrate, for top contact devices the
growth interface is the contact interface between organic
semiconductor layer and dielectric layer. Growth interface with
large roughness is easy to induce nucleation when crystallizing,
and orientation and alignment of crystals are thus random. (H. Li
et al., MRS Bulletin, 1, 38(2013)). The root mean square roughness
(RMS), a parameter for roughness characterization, refers to the
root mean square value of the contour deviation from the average
line within the sampling length. Therefore, smooth or flat growth
interface with very low roughness is the prerequisite for uniform
growth of organic crystals. Moreover, smooth or flat growth
interface are needed to achieve uniform growth of organic
single-crystalline semiconductor thin film with high effective
coverage ratio or even complete/full coverage.
[0014] However, in organic single-crystalline semiconductor devices
based on bottom contact structure, thus organic single-crystalline
semiconductor layer is deposited on a bottom contact substrate.
Organic semiconductor layer as active layer is key to device
function, the organic semiconductor layer aforementioned is
composed of organic single-crystalline semiconductor thin film, and
the organic single-crystalline semiconductor thin film is
consisting of multiple crystals, the crystals aforementioned are
from semiconductor and exist as single-crystalline states.
Source/drain electrodes, with key functions as injecting and
extracting charge carriers, are located on the growth interface,
which is perpendicular to the direction of crystal growth. To
obtain working electrodes, source/drain electrodes usually have
certain thickness over 10 nanometers and even some of them could be
up to tens of nanometers, where the roughness of growth interface
is greatly increased. It could be assumed that semiconductor
devices based on bottom contact structure has rough growth
interface, and the RMS of rough growth interface is several or even
dozens of times that of smooth growth interface. The source/drain
electrodes construct barriers like high hills, thereby the
nucleation and front growth of crystals are influenced, resulting
in less ordering of molecular packing. It makes the crystals unable
to achieve uniform growth when crossing the electrodes. That is,
the morphology change of the crystal appears before crossing the
electrode 100, at the electrode edges 101 or 103, on the electrode
102, or after crossing the electrode 104, therefore, hindering the
efficient charge transport of carriers as well as increasing the
anisotropy of charge transport. Ultimately, the electrical
performance of semiconductor devices is greatly reduced. The
morphology change of crystals refers to the change that is easy to
be observed. Specifically, it can refer to the change that can be
observed under an optical microscope or a polarized optical
microscope with appropriate magnification. FIG. 9 is a schematic
diagram of various morphology changes of crystals. For instance,
packing defects and deformation of crystals occur near the edges of
electrodes, the deformation above-mentioned including cracks, pits
and distortion of crystals and so on (FIG. 9F). Width change (FIG.
9C--FIG. 9D), shape change (FIG. 9G) and curving (FIG. 9H) of
crystals are also included. Besides, the alignment of crystal
arrays are easily affected by electrodes, leading to branching,
intersection, and alignment disturbance (FIG. 9E). In the FIG. 10
of polarized optical micrograph, the actual morphology changes of
crystals could be observed. Both growth direction and width of
crystals on electrodes changed in FIG. 10A-FIG. 10B. Deformation
and defects of crystals were shown at the edges of electrodes in
FIG. 10C and FIG. 10F. In FIG. 10D-FIG. 10E, the curving and
branching of crystals appeared.
[0015] In view of the above-mentioned problems, the improvements of
current technology are included as follows: patterning the
substrates for modifying alignment of crystals externally. However,
this method relies on patterned templates, which requires
sophisticated micro channels with extra preparation process. Here,
the crystal growth is modified and constrained by the micro
channels in the meantime. The effective coverage ratio reported in
this article only has one dimension in vertical direction, and the
f.sub.cp is about 15-30%, which means it cannot achieve
sufficiently high effective coverage ratio at both lengthwise and
vertical direction of crystal growth, far from meeting the
requirements of high-performance devices (W. Deng et al., Materials
Today, 24, 17(2019)). Since the control on morphology of organic
semiconductor single crystals is difficult, to circumvent this
problem, adjusting the material composition are adopted to achieve
large-scale growth. For example, blending organic semiconductor
small molecules with insulting polymers to replace organic
semiconductor single crystals is used to avoid the problem, as it
mentioned in (M. Niazi et al., Nature Communications, 6, 8598
(2015)), "The stringent performance requirements for organic
thin-film transistors (OTFTs) in terms of carrier mobility,
switching speed, turn-on voltage and uniformity over large areas
require performance currently achieved by organic single-crystal
devices, but these suffer from scale-up challenges. Here we present
a new method based on blade coating of a blend of conjugated small
molecules and amorphous insulating polymers to produce OTFTs".
Although this method has improved the morphology of thin-film
devices on bottom contact structure in some degree, the performance
of material is sacrificed. Because of the bending with insulting
polymers, organic semiconductor thin film are no longer
single-crystalline. The thin film obtained has phase separation,
and the phase separation is limited by the modification layer on
electrodes in different area. When insulating polymers are
sandwiched between the organic semiconductor layers inside of the
blends, the compactness of crystalline films is affected. If
insulating polymers are located at the outer surface of blends, the
contact resistance between semiconductor layer and electrodes,
resulting in deteriorating the electrical performance of devices.
Transferring previously prepared crystals from vapor phase method
or liquid phase method via flexible substrate are of certain could
be applied on substrates with pre-deposited electrodes to fabricate
bottom contact devices. For instance, physical transfer method or
chemical etching method are included. Nevertheless, there are still
some problems existed in transfer method: 1) the transferring is
challenging, damage on crystals might appear during the transfer
process; 2) contact issues of devices are exhibited, and intimate
contact might be impeded when laminating crystals from original
flexible substrates to target substrates with pre-deposited
electrodes; 3) the procedures are not facile, and it is difficult
to laminate crystals precisely at designated locations, leading to
reduction of device integration, as well as hampering the
large-scale production. Therefore, in a perspective of
industrialization, utilizing in-situ grown organic
single-crystalline semiconductor layer is an ideal way to fabricate
bottom contact devices.
[0016] In a conclusion, the ideal organic semiconductor devices for
industry application are organic single-crystalline semiconductor
devices based on bottom contact structure. The organic
single-crystalline semiconductor thin film aforementioned has a
morphology of uniform growth, and it is able to achieve sufficient
high effective coverage ratio even complete/full coverage of
morphology on a substrate of arbitrary shape or arbitrary size. The
morphology of uniform growth refers to the crystal morphology
remaining basically unchanged before crossing the electrode 100, at
the electrode edges 101 and 103, on the electrode 102, and after
crossing the electrode 104. Channels with highest quality for
efficient charge transport of carriers are provided, thus optimal
device performance could be guaranteed. However, current technology
cannot prepare organic single-crystalline semiconductor devices
based on bottom contact structure with morphology of uniform
growth. There are several challenges: 1) only on smooth or flat
growth interface with extremely low roughness, organic
single-crystalline semiconductor thin films with morphology of
uniform growth could be obtained. However, pre-deposited electrodes
on bottom contact substrates have greatly increased the roughness
of growth interface. Consequently, organic single-crystalline
semiconductor thin films with morphology of uniform growth are
unavailable; 2) organic single-crystalline semiconductor thin films
have relatively low effective coverage ratio in organic
single-crystalline semiconductor devices. It is hard to improve the
effective coverage ratio. Furthermore, it is impossible to achieve
a sufficiently high effective coverage ratio in both the lengthwise
direction and the vertical direction at the same time, which is far
from meeting the requirement of excellent device performance; 3) in
order to achieve effective coverage ratio as large as possible,
preparation of organic single-crystalline semiconductor thin film
with complete/full coverage on a substrate of arbitrary shape or
arbitrary size is demanded. Theoretically, a smooth or flat growth
interface is required. Because of the non-smooth growth interface
of devices based bottom contact structure, it cannot obtain an
organic single-crystalline semiconductor thin film with
complete/full coverage on bottom contact structure; 4) since
organic semiconductor single crystals require periodical molecular
packing inside, the extraordinary control over morphology is
needed. The growth condition is very strict, thus combining single
crystallinity of materials with morphology of uniform growth and
high effective coverage ratio is incapable. However, ideal devices
need to satisfy the requirements above-mentioned at the same time.
That is, acquiring organic single-crystalline semiconductor thin
films on bottom contact growth interface with morphology of uniform
growth and high effective coverage ratio. Unfortunately, it cannot
be realized by current technology; 5) the control over growing
organic semiconductor single crystals is very complicated for
sophisticated modification on morphology, and it is difficult to
achieve large-scale industry production; 6) for industrialization,
it is incapable of realizing unlimited in-situ growth of organic
single-crystalline semiconductor thin film on a bottom contact
substrate of arbitrary shape or arbitrary size. Current
technologies have not solved any of the problems aforementioned,
not to say that solving 6 problems above-mentioned at a same time.
Therefore, huge challenges are raised, such as getting uniformly
grown organic single-crystalline semiconductor thin films in bottom
contact structure, realizing complete/full coverage of morphology
on a substrate of arbitrary shape or arbitrary size. The challenges
aforementioned may act as roadblocks for large-scale industry
application of organic single-crystalline semiconductor
devices.
SUMMARY
[0017] In view of the shortcomings of the current technology, the
technical problem to be solved by the present invention is to
provide an organic single-crystalline semiconductor structure and a
preparation method thereof. Based on the problems existing in the
prior art, the inventors overcome obstacles in the prior art and
limitations in thinking. Unexpectedly, organic single-crystalline
semiconductor thin films with morphology of uniform growth and high
effective coverage ratio are successfully prepared on the growth
interface in bottom contact structure, even complete/full coverage
could be achieved. Besides, unlimited in-situ growth of organic
single-crystalline semiconductor thin film are able to realize on a
bottom contact substrate of arbitrary shape or arbitrary size. The
6 problems of organic single-crystalline semiconductor devices
based on bottom contact structure that are insoluble in the prior
art could be resolved simultaneously in the present invention. For
organic semiconductor devices, the organic single-crystalline
semiconductor thin films aforementioned have satisfied the most
ideal situation of both morphology and material, which is essential
for realizing ideal organic semiconductor devices for industrial
application. The organic singe-crystalline semiconductor thin film
provides high-quality channels with maximize area for efficient
charge transport of carriers. In the field of industry, organic
semiconductor devices based on organic single-crystalline
semiconductor structure aforementioned have multiple advantages:
such as best performance of charge transport, highest device
integration, best stability, facile preparation, combination with
flexibility, possibility of realizing in-situ complete/full
coverage and so on. This offer a foundation for large-scale
industrial preparation of in-situ organic semiconductor devices
within almost ideal situations above-mentioned, which is breaking
through the bottleneck of current technology.
[0018] The present disclosure adopts the following technical
solutions:
[0019] The first technical problem to be solved by the present
disclosure is to provide an organic single-crystalline
semiconductor structure. The structure comprises substrate,
growth-assistant layer, electrodes and organic single-crystalline
semiconductor layer. The last three are deposited sequentially from
bottom to top on the substrate. The organic single-crystalline
semiconductor layer aforementioned is grown on the growth-assistant
layer and electrodes and is also in contact with them. The organic
single-crystalline semiconductor layer is consisting of organic
single-crystalline semiconductor thin film, and the thin film is
constructed by organic semiconductor single crystal arrays. The
morphology of organic semiconductor single crystal array keeps
basically unchanged before crossing the electrode 100, at the
electrode edges 101 and 103, on the electrode 102, and after
crossing the electrode 104. That is, the organic single-crystalline
semiconductor thin film of present invention has a morphology of
uniform growth.
[0020] The organic semiconductor single crystal array is composed
by crystals. The material of crystals is semiconductor, and the
crystals exist as single-crystalline states. The basically
unchanged morphology of organic semiconductor single crystal array
refers to basically unchanged crystal morphology as well as
consistent alignment before and after crossing the electrodes. The
basically unchanged crystal morphology could refer to each crystal
in the organic semiconductor single crystal array remaining
basically unchanged in growth direction, crystal width, crystal
shape and consistence of growth. The basically unchanged morphology
of organic semiconductor single crystal array refers to its
morphology of uniform growth.
[0021] The morphology of organic single-crystalline semiconductor
thin film containing: the morphology of organic semiconductor
single crystal array, the morphology of crystal and the alignment
of organic semiconductor single crystal array. The morphology
aforementioned could be characterized by optical microscopy,
scanning electron microscopy, atomic force microscopy and so on.
Currently, optical microscopy is the most commonly used method with
the largest scale of characterization and also the easiest way to
promote. For example, the specific characterization method of
optical microscopy is described as follows: the organic
semiconductor structure aforementioned is placed under the optical
microscope with appropriate magnification (it could be tens or
hundreds of times, for instance, FIG. 8 is with the magnification
of 100 times). Next is capturing the optical microscope image and
polarized optical microscope image (i.e. optical microscope image
between crossed-polarizers) of organic single-crystalline
semiconductor thin film. The images of organic single-crystalline
semiconductor thin film above-mentioned should contain areas before
crossing the electrode, at the electrode edges, on the electrode,
and after crossing the electrode at the same time. Then, the
morphology of organic single-crystalline semiconductor thin film in
both images should be analyzed. When uniform color or the change of
color appears, it could be inferred that crystals obtained is not
single-crystalline (as illustrated in FIG. 10B-FIG. 10F, the
emergence of different color patch and color change account for
polycrystalline organic semiconductor thin film). The crystals with
the basically uniform color are single crystals (as illustrated in
FIG. 11, crystals have basically uniform color in itself and
between each other as well). By observing the obtained optical
microscope images or polarized optical microscope images, it can be
determined whether the morphology of the organic semiconductor
single crystal array is basically unchanged, that is, whether the
organic semiconductor single crystal array has a uniform growth
morphology.
[0022] The opposite concept of "the morphology of the organic
semiconductor single crystal array is basically unchanged" is "the
morphology of the organic semiconductor single crystal array is
changed", which could refer to the change in the crystal morphology
and/or the inconsistent alignment of the organic semiconductor
single crystal array before and after crossing the electrodes.
Whether the change of crystal morphology or the inconsistent
alignment of the organic semiconductor single crystal array before
and after crossing the electrode, it could be regarded as "the
morphology change of the organic semiconductor single crystal
array".
[0023] The opposite concept of "basically unchanged crystal
morphology" is "changed crystal morphology". The change of crystal
morphology could be referred to the change of any parameters of
crystal growth for each crystal that constitutes the organic
semiconductor single crystal array, including the growth direction
of crystal, crystal width, and crystal shape. For example, the
change of morphology could be visualized in optical microscope
images or polarized optical microscope images: the packing defects
of crystals near the edges of electrodes, deformation of crystals
near the edges of electrodes such as cracks, pits, distortion and
so on (FIG. 9F), the change of crystal width (FIG. 9C-FIG. 9D), the
change of crystal shape (for example, spherulites at the electrodes
in FIG. 9G) and curving of crystals (FIG. 9H). The change of
crystal width aforementioned refers to the absolute value of the
ratio (|R|) of the difference between the width of the crystal at
the edge of the electrode 101 and 103 and the edge of the electrode
103 over 20%, that is, |R|>20%.
|R|=(|(k.sub.1(101)-k.sub.1(103))/k.sub.1(103)|+|(k.sub.2(101)-k.sub.2(10-
3))/k.sub.2(103)|+ . . .
+|(k.sub.n(101)-k.sub.n(103))/k.sub.n(103)|)/n*100%, k.sub.1(101),
k.sub.2(101), . . . , k.sub.n(101) are the widths of the 1, 2, . .
. , n crystals in contact with the electrode edge 101,
respectively, k.sub.1(103), k.sub.2(103), . . . , k.sub.n(103) are
the widths of the 1, 2, . . . , n crystals in contact with the
electrode edge 103, where n is a positive integer greater than or
equal to 8, as shown in FIG. 9D. FIG. 10 are polarized optical
microscope images, some practical phenomena of the change of
crystal morphology could be observed. In FIG. 10A-FIG. 10B, the
growth direction and width of crystals on the electrodes had
observable changes. In FIG. 10C and FIG. 10F, defects and
deformation of crystals occurred at the edges of electrodes. In
FIG. 10D-FIG. 10E, the curving of crystal was visualized.
[0024] The opposite concept of "the alignment of the organic
semiconductor single crystal array is consistent before and after
crossing the electrode" is that "the alignment of the organic
semiconductor single crystal array is inconsistent before and after
crossing the electrode". That is, organic semiconductor single
crystal array has inconsistent orientation before crossing the
electrode 100, at the electrode edges 101 and 103, on the electrode
102, and after crossing the electrode 104. For example, in the
optical microscope images or polarized optical microscope images,
the orientation of crystal array was easily affected by electrodes,
leading to branching, intersection, and alignment disturbance FIG.
9E. In FIG. 10D-FIG. 10E, the branching crystals were shown.
[0025] Compared with those thin films with morphology change, the
present invention provides a high-quality organic
single-crystalline semiconductor thin film with a morphology of
uniform growth, and improves the performance of charge carrier
injection, transport and extraction. Also, the charge carriers can
be efficiently injected and extracted at the contact with
electrodes (i.e. at the edges of electrodes and on the electrodes),
which is beneficial for realizing the intrinsic performance of
organic semiconductor single crystals. And the challenges that
charge traps/structural defects are easily occurred at the contact
with electrodes in the organic single-crystalline semiconductor
devices with bottom contact structure in the prior art are
overcome.
[0026] In some embodiments, the organic semiconductor single
crystal array aforementioned is obtained by uniform growth crossing
the electrodes, and the organic semiconductor single crystal array
is constituted by aligned crystals, as shown in FIG. 8, FIG. 9A-9B,
and FIG. 11. The uniform growth crossing the electrodes refers to
crystals that constitute the organic semiconductor single crystal
array are uniformly growing before crossing the electrode 100, at
the electrode edges 101 and 103, on the electrode 102, and after
crossing the electrode 104. Thus, the morphology of organic
semiconductor single crystal array keeps basically unchanged before
crossing the electrode 100, at the electrode edges 101 and 103, on
the electrode 102, and after crossing the electrode 104. The term
"before the electrode 100 and after the electrode 104" refers to
the growth area of the crystals before and after encountering the
electrodes along the crystal growth direction, respectively; the
term "electrode edges 101 and 103" refers to the edges where the
electrodes are in contact with growth-assistant layer. As displayed
in FIG. 5, FIG. 8, and FIG. 9A-9B, the perfect morphology is
ribbon-like crystal array with approximately linear
arrangement.
[0027] The growth-assistant layer is necessary for realizing
uniform growth of organic single-crystalline semiconductor thin
film crossing the electrodes. During the nucleation and
crystallization process of organic semiconductor molecules, the
growth-assistant layer plays an essential part in modification for
packing ordering, as well as the distribution, degree and
interaction of organic semiconductor molecular aggregates. It
contributes for improving the situation that crystal growing is
hindered by the height difference between the electrodes and the
plain substrate without pre-deposited electrodes. There is a huge
difference in surface chemistry between the electrodes and the
plain substrate without pre-deposited electrodes, thus, morphology
is usually changed at the contact with electrodes such as increased
grain boundaries, reduced grain size and so on. In some cases,
completely different molecular stacking modes might be caused on
the electrodes or near the electrodes compared with those on the
plain substrate without pre-deposited electrodes. However, the
growth-assistant layer reduces this difference, it assists the
growth of organic semiconductor crystals crossing the electrodes
with basically unchanged morphology. On the other hand, the
growth-assistant layer is also helpful for improving wetting of
solutions containing organic semiconductors, which is optimal for
achieving complete/full coverage of organic single-crystalline
semiconductor thin film.
[0028] In some embodiments, the organic single-crystalline
semiconductor thin film can realize complete/full coverage on a
substrate of arbitrary shape or arbitrary size. That is, the growth
of organic single-crystalline semiconductor thin film on the
substrate is not restricted by the shape or size of the substrate.
The complete/full coverage refers to the organic single-crystalline
semiconductor thin film having sufficiently high effective coverage
ratio at both lengthwise direction and vertical direction of
crystals.
[0029] In some embodiments, the complete/full coverage could refer
to effective coverage ratio at lengthwise direction of crystal
(lengthwise directional effective coverage ratio)
f.sub.cr.gtoreq.80%, and the effective coverage ratio at vertical
direction of crystal (vertical directional effective coverage
ratio) f.sub.cp.gtoreq.50%.
[0030] Preferably, f.sub.cr.gtoreq.90%, f.sub.cp.gtoreq.5 0%.
[0031] More preferably, f.sub.cr.gtoreq.80%,
f.sub.cp.gtoreq.80%.
[0032] As the most preferably, f.sub.cr.gtoreq.90%,
f.sub.cp.gtoreq.80%.
[0033] In some embodiments, for the lengthwise directional
effective coverage ratio f.sub.cr+(c.sub.L1+c.sub.L2+ . . .
+c.sub.Lm)/(L.sub.1+L.sub.2+ . . . +L.sub.m), m is a positive
integer greater than or equal to 5, c.sub.L1, c.sub.L2, . . . ,
c.sub.Lm represent continuous lengths of crystals c.sub.L in the 1,
2, . . . , m channels in m adjacent and continuous channels,
respectively. And L.sub.1, L2, . . . , L.sub.m represent the
lengths L of the 1, 2, . . . , m channels covered by crystals,
respectively. For the vertical directional effective coverage
ratio, f.sub.cp=(k.sub.1+k.sub.2+ . . . +k.sub.n)/W, k.sub.1,
k.sub.2, . . . , k.sub.n represent the contact widths k between the
1, 2, . . . , n crystals and source/drain electrodes, respectively,
W represents width of channel, n is a positive integer greater than
or equal to 8.
[0034] In order to achieve the possible maximum effective coverage
ratio of organic single-crystalline semiconductor thin film at both
the lengthwise direction and the vertical direction simultaneously
in the continuous channels (i. e. sufficiently high effective
coverage ratio at both the lengthwise direction and the vertical
direction simultaneously), complete/full coverage of organic
single-crystalline semiconductor thin film needs to be realized on
a substrate of arbitrary shape or arbitrary size. There are two
indicators to evaluate whether the complete/full coverage is
achieved: the effective coverage ratio in the lengthwise direction
and the effective coverage ratio in the vertical direction. When
f.sub.cr.gtoreq.80% and f.sub.cp.gtoreq.50%, efficient charge
transport pathways are able to be provided for carriers as well as
better electrical performance. Therefore, if the two indicators are
met, it could be considered as achieving the complete/full
coverage. At present, in this field, the technology for preparing
large-area organic single-crystalline semiconductor thin films is
limited in the laboratory, and the complete/full coverage on a
substrates of arbitrary shape or arbitrary size cannot be
achieved.
[0035] The effective coverage ratio of single-crystalline organic
semiconductor thin film reported in the prior art only has one
indicator, which represents the effective coverage ratio in the
vertical direction. It declares that organic single-crystalline
semiconductor thin film in the prior art can only achieve effective
covering in the vertical direction, but not in the lengthwise
direction. Further, the effective coverage ratio in the vertical
direction reported is generally low, indicating that the
complete/full coverage described in the present invention cannot be
obtained in the prior art. For example, as illustrated in FIG. 22,
FIG. 22A and FIG. 22A-22B are FIGS. 2(d) and 4(a) in W. Deng et
al., Materials Today, 24, 17 (2019), respectively. The arrow's
direction in the figure represents the lengthwise direction, and
the vertical direction is the direction perpendicular to the arrow'
direction. The article mentioned that the coverage ratio of DPA
crystals in one direction is only 15-30% ("the surface coverage of
DPA crystals on the substrate is estimated to be about 15-30%",
FIGS. 2(d) and 4(a)). Through the arrow's direction in FIG.
22A-22B, it can be deduced that the surface coverage described in
the text represents the effective coverage ratio in the vertical
direction. In addition, those skilled in the art can understand
that the range of the selected area where the morphology of organic
single-crystal thin film is characterized could be deduced by the
scale bar in the morphology characterization images. The scale bar
in FIG. 22A is 20 .mu.m, it shows that a tiny area is selected in
the entire substrate (a 4-inch silicon wafer, with a diameter about
100 mm) to characterize the morphology of the organic
single-crystal thin film. It further shows that it is impossible to
obtain effective coverage ratio in both directions completely. In
summary, sufficiently high effective coverage ratio in the two
dimensions including the lengthwise direction and the vertical
direction cannot be achieved simultaneously in the prior art. And
it is far from meeting the requirements of high-performance
devices, which is a huge technical challenge. However, the organic
single-crystalline semiconductor thin films with a complete/full
coverage are able to overcome this problem, based on which more
complex organic semiconductor heterostructures can be fabricated
additionally, and more diversified functions in
electronics/optoelectronics could be developed. Moreover, organic
single-crystalline semiconductor thin films with high effective
coverage ratio can be used for preparing highly integrated
electronic device arrays, which provides a possibility for
developing new-generation integrated devices. The
large-size/large-area/large-scale organic single-crystalline
semiconductor thin film mentioned in the prior art were able to be
prepared only on a smooth or flat substrate with a regular size in
micrometers or several centimeters. And the complete/full coverage
of organic single-crystalline semiconductor thin film cannot be
achieved on rough substrates in bottom contact structure, not to
mention on a substrate of arbitrary shape or arbitrary size. While
the large-area organic single-crystalline semiconductor thin film
provided by the present invention can realize unlimited continuous
growth on a bottom contact substrate, and a complete/full coverage
of organic semiconductor single crystal array up to tens of
centimeters can be obtained.
[0036] In some embodiments, the electrodes contact with the
growth-assistant layer with protruding outside of the
growth-assistant layer. The electrodes are in contact with the
growth-assistant layer in an upper type and/or embedded type, the
upper type refers to the upper surface of growth-assistant layer in
contact with the lower surface of the electrodes, and the embedded
type refers to the electrodes half-embedding or penetrating the
growth-assistant layer. The growth-assistant layer is located
underneath the electrodes, as shown in FIG. 4, the electrodes are
in contact with growth-assistant layer in an upper type and/or
embedded type, the upper type (FIG. 4A) means that the upper
surface of the growth-assistant layer is in contact with the lower
surface of the electrode, and the embedded type (FIG. 4B) means
that the electrodes are half-embedding or penetrating the
growth-assistant layer. The half-embedding specifically refers to
the growth-assistant layer in contact with both the lower surface
and the side surface of the electrodes. The penetrating
specifically refers to the growth-assistant layer contacting only
with the side surface of the electrodes. The electrodes are
arranged on growth-assistant layer in either or both of the upper
type and the embedded type (FIG. 4C). Therein the electrodes can be
arranged in contacting with growth-assistant layer only in the
upper type, or only in the embedded type, and it can also be in
both the upper type and the embedded type at the same time. The
arrangement of electrodes aforementioned could be ordered or
random.
[0037] The location relationship that the growth-assistant layer
beneath the electrodes could be achieved by depositing the
growth-assistant layer before the electrodes. By partially etching
the growth-assistant layer using ultraviolet ozone/laser/plasma or
other methods after depositing it and then depositing the
electrodes in etched pits, the location relationship that the
growth-assistant layer with embedded electrodes can be achieved.
When the growth-assistant layer is located above the electrodes, it
will separate the organic semiconductor layer from the electrodes,
so that carriers cannot be directly injected into the organic
semiconductor layer from the electrodes because of the hinderance
from the growth-assistant layer, resulting in device failure.
Therefore, the location relationship that the growth-assistant
layer beneath the electrodes or with the electrodes embedded can
ensure the uniform growth of organic single-crystalline
semiconductor thin film across the electrodes while maintaining the
integrity function of the organic semiconductor device.
[0038] In some embodiments, as FIG. 5 displayed, the organic
single-crystalline semiconductor thin film is a well-aligned
organic semiconductor single crystal array, which is composed of
multiple separate and independent linear-type elements (the black
solid stripes in the left side of FIG. 5). The multiple linear
elements are arranged in a linear-type arrangement, and the
linear-type arrangement may refer to the well-aligned
orientation/arrangement of the linear elements along the crystal
growth direction. The "well-aligned orientation/arrangement" could
mean that the linear elements are almost parallel. The linear
elements grow uniformly before crossing the electrode 100, at the
electrode edges 101 and 103, on the electrode 102 and after
crossing the electrode 104, that is, the morphology of the linear
element is basically unchanged before crossing the electrode 100,
at the electrode edges (101 and 103, on the electrode 102 and after
crossing the electrode 104, the linear element is an independent
crystal with single-crystalline morphology.
[0039] In some embodiments, the well-aligned
orientation/arrangement may refer to the degree of orientation
F.gtoreq.0.625; preferably, F.gtoreq.0.95; more preferably, F=1
(the linear elements are parallel to each other).
[0040] In some embodiments, the detection method of F is: randomly
selecting n linear elements of the organic single-crystalline
semiconductor thin film as samples, where n is a positive integer
greater than or equal to 10. And the crystal growth direction is
taken as the reference direction. Take the angle between the
direction of the longest dimension c of each linear element and the
reference direction as the orientation angle A, the average value
of the orientation angles of the n linear elements as . And the
degree of orientation F=0.5*(3*cos.sup.2 -1).
[0041] In some embodiments, the morphology of the linear element is
pseudo one-dimensional (pseudo 1D, p1D) or pseudo two-dimensional
(pseudo 2D, p2D); when the length c of a single crystal along the
crystal growth direction is much larger than the width a of the
crystal and the thickness b of the crystal, that is, when
c/a.gtoreq.500 and c/b.gtoreq.500, the morphology is pseudo 1D;
preferably, c/a.gtoreq.1000, c/b.gtoreq.1000; more preferably,
c/b.gtoreq.2000, a/b.gtoreq.2000; when both the length c of a
single crystal along the crystal growth direction and the width a
of the crystal are much larger than the thickness b of the crystal,
that is, when c/b.gtoreq.500 and a/b.gtoreq.500, the morphology is
pseudo 2D; preferably, the linear element has a pseudo
one-dimensional morphology; as the most preferable, the pseudo 1D
linear element is a regular strip or ribbon.
[0042] In some embodiments, in the stereogram of linear element
(FIG. 5), the top view of linear element is linear or facial form,
and the thickness b of linear element is 2 nm to 400 nm;
preferably, b is 5 nm to 200 nm.
[0043] In some embodiments, the thickness of linear element is
highly uniform.
[0044] In some embodiments, the detection method of "the thickness
of linear element is highly uniform" is: randomly taking p samples
of linear elements in the organic single-crystalline semiconductor
thin film and characterizing the thickness b of the linear
elements, the average thickness of p linear elements is b, and p is
a positive integer greater than or equal to 8, when b<10 nm, the
coefficient of variation of the thickness of the linear element in
p samples is .ltoreq.40%, when 10 nm.ltoreq.b.ltoreq.50 nm, the
coefficient of variation of the thickness of the linear element in
p samples is .ltoreq.30%, when b.gtoreq.50 nm, the coefficient of
variation of the thickness of the linear element in p samples is
.ltoreq.20%, indicating that linear elements have highly uniform
thickness; preferably, when b.ltoreq.10 nm, the coefficient of
variation of the thickness of the linear element in p samples is
.ltoreq.30%, when 10 nm.ltoreq.b.ltoreq.50 nm, the coefficient of
variation of the thickness of the linear element in p samples is
.ltoreq.20%, when b.gtoreq.50 nm, the coefficient of variation of
the thickness of the linear element in p samples is .ltoreq.10%.
The coefficient of variance is also called the "standard deviation
rate", which is the ratio of the standard deviation to the mean
multiplied by 100%. The coefficient of variation is an absolute
value that reflects the degree of dispersion of the data. The
smaller the value of the coefficient of variation, the smaller the
degree of dispersion of the data, indicating that the thickness of
crystals is more uniform.
[0045] In some embodiments, the gap width g of each of the linear
elements along the crystal growth direction is 0 mm to 1 mm;
preferably, the gap width g.ltoreq.10 .mu.m.
[0046] The linearly arranged organic single-crystalline
semiconductor thin film has well-aligned orientation/arrangement,
providing a high-quality efficient transport pathway for charge
carriers, as shown in FIG. 8 and FIG. 9A-9B, where FIG. 8 is the
optical microscope image of organic single-crystalline
semiconductor thin film that actually obtained. FIG. 9A-9B is the
corresponding schematic diagram of FIG. 8, each black solid stripe
in FIG. 9A-9B is a crystal, and each crystal is a linear element.
FIG. 9B is a partial enlarged view within the dashed frame in FIG.
9A. The organic single-crystalline semiconductor thin film with
regularity, uniform thickness, and well-aligned
orientation/arrangement ensures the uniformity of the device, which
is beneficial to control the resistance of the semiconductor
devices and further improve the electrical performance of the
devices. Organic single-crystalline semiconductor thin films with a
perfect morphology on an industrial scale can only be obtained by
coupling the ability to achieve complete/full coverage on
substrates of arbitrary shape or arbitrary size with the above
three properties simultaneously. These organic single-crystalline
semiconductor thin films greatly increase the utilization area of
devices, and make the evaporation of electrodes and the preparation
of highly integrated devices more convenient, eventually the
technical difficulties that organic single-crystalline
semiconductor devices are difficult to integrate for industry are
overcome.
[0047] Single crystals grown by small molecules of
easy-crystallized organic semiconductors are now commercially
available. If the thickness of the single crystal array is less
than 2 nm, some defects may exist on the surface or inside of the
single crystal obtained, thus the performance of charge carriers
transport without doping might be reduced due to the defects as
charge traps. If the thickness of the single crystal array exceeds
400 nm, the material consumption increases, and the access
resistance of the device also increases, which causes an increase
in the device's demand for operating voltage, the threshold voltage
becomes larger as well, ultimately the device performance would be
affected. In addition, due to the flexibility of the dielectric
layer, the roughness and undulation of the upper surface of the
dielectric layer coated on single crystals will be affected by the
thickness of the organic single-crystalline semiconductor thin
film, which may cause poor contact between gate electrodes and the
dielectric layer. Therefore, appropriate thickness of the linear
element can ensure the preparation of high-performance devices
while saving the cost of raw materials.
[0048] In some embodiments, the growth-assistant layer is an
organic insulating thin film. Preferably, the water contact angle
CA.sub.water that between the organic insulating thin film
aforementioned and water is 30.degree. to 120.degree.; more
preferably, the CA.sub.water is 60.degree. to 100.degree..
[0049] In some embodiments, the material of the organic insulating
film has a .pi.-conjugated system, and the .pi.-conjugated system
refers to a system wherein conjugated .pi. bonds are able to form.
And the it-conjugation could be extended by conjugated units.
[0050] In some embodiments, the dielectric constant of the organic
insulating film is .ltoreq.20; preferably, the dielectric constant
is .ltoreq.12.
[0051] In some embodiments, the material of organic insulating film
is selected from any one or more of self-assembled small molecules
containing silyl groups, self-assembled small molecules containing
phosphate groups, self-assembled small molecules containing thiol
groups, dielectric polymers.
[0052] In some embodiments, the material of the organic insulating
film is a dielectric polymer or a mixture thereof, and the selected
polymer is crosslinked or non-crosslinked; preferably, the polymer
contains any one or more blocks from polystyrene, polymethyl
methacrylate, polyvinyl alcohol, polyvinyl chloride,
polyvinylpyrrolidone, polysiloxane, polyimide, polyethylene,
polyethylene oxide, polyvinylphenol, polyethylene naphthalate,
polyethylene terephthalate, polyethersulfone, benzocyclobutene,
perfluoroalkyl vinyl ether, polyfluoroethylene.
[0053] Coating growth-assistant layer on the substrate can be used
to assist crystals to achieve uniform growth crossing the
electrodes, and organic single-crystalline semiconductor thin films
with well-aligned orientation/arrangement could be obtained. Since
the growth-assistant layer is located beneath the organic
single-crystalline semiconductor thin film and the electrodes, its
properties will affect the injection and extraction of the
electrodes in devices. Thus, organic insulating materials should be
adopted for the growth-assistant layer, otherwise it may result in
a normally open state in the device, that is, there will be still a
current flowing even at 0V, which consumes a lot of energy and the
switching effect cannot be realized. The surface of
growth-assistant layer has a certain degree of hydrophobicity.
Choosing a material with a suitable water contact angle can ensure
that the interface is partially hydrophobic but not too hydrophobic
to reduce the affinity with organic solvents, which is conducive to
increasing the affinity between growth interface and organic
solution. This enables crystals to grow continuously on the surface
of the substrate with pre-deposited electrodes and to across the
certain-height electrodes without changing the morphology. And the
crystal quality of the well-aligned organic single-crystalline
semiconductor thin film grown will be improved, thereby the
stability of the device based on this structure is enhanced. The
specific material of growth-assistant layer can be determined
according to the selected molecules of semiconductor layer and the
type of organic solvent. Preferably, the growth-assistant layer has
a .pi.-conjugated structure, thus, it would lead to interactions
with organic semiconductor molecules which also have a
.pi.-conjugated system. A guiding effect on the arrangement and
stacking of molecules could be obtained. The dielectric constant
reflects the polarity and density of atoms and bonds in the
growth-assistant layer. And a smaller dielectric constant usually
means a low polarity of the growth-assistant layer. It is helpful
to increase the affinity of commonly used organic solvents with low
polarity, a good growth environment for obtaining a complete/full
coverage morphology of organic semiconductor single crystals is
provided. The self-assembled layer of small molecules containing
silyl groups, phosphate groups, and thiol groups can form a dense
buffer layer, and the variable modification of groups can play a
guiding role for the molecular arrangement and stacking of organic
semiconductor materials with different structures. The dielectric
polymers as growth-assisted layer have good compatibility with
organic semiconductors. It is easy to obtain high-quality interface
of growth-assisted layer with convenient prepared dielectric
polymers. Also, the interface chemical properties can be adjusted
by modifying the side groups of the polymer.
[0054] In some embodiments, the core of the material of the organic
single-crystalline semiconductor thin film contains a
.pi.-conjugated structure, with a band gap width .ltoreq.3.5 eV.
Preferably, the organic semiconductor material is small organic
semiconductor molecules; more preferably, the small organic
semiconductor molecules are selected from any one of linear acenes,
linear heteroacenes, benzothiophene, perylene, diphenylanthracene,
fullerene and their respective derivatives.
[0055] The small molecules of organic semiconductors refer to the
organic semiconductor material with a fixed molecular weight and a
well-defined molecular structure. The width of band gap is the
energy difference between the top of the valence band and the
bottom of the conduction band in insulators and semiconductors,
also known as the forbidden bandwidth. The .pi.-conjugated system
refers to a system wherein conjugated .pi. bonds are able to form.
Proper band gap width ensures the display of intrinsic
characteristics of organic semiconductors and the tailoring of
field-effect can be realized. The core of linear acenes, linear
heteroacenes, benzothiophene, perylene, diphenylanthracene,
fullerene and their respective derivatives contains .pi.-conjugated
structure, high-quality organic single-crystalline semiconductor
thin film could be easily obtained due to their good crystallinity.
For example, 6,13-bis(triisopropylsilylethynyl)pentacene
(TIPS-pentacene) and 2,7-dioctyl[1]benzothieno[3,2-b][1]
benzothiophene (C.sub.8--BTBT) have a certain length of silane
chain or alkane chain side groups, their solubility in organic
solvents is good, which is conducive to the realization of
complete/full coverage growth of organic single-crystalline
semiconductor thin films.
[0056] In some embodiments, the organic semiconductor single
crystal array is obtained by in-situ uniform growth crossing the
electrodes. The organic semiconductor single crystal array provided
by the present invention is directly in-situ grown via solution
methods on a substrate with pre-deposited source/drain electrodes.
The in-situ uniform growth crossing the electrodes means that the
crystals constituting the organic semiconductor single crystal
array grow uniformly before crossing the electrodes 100, at the
electrode edges 101 and 103, on the electrodes 102 and after
crossing the electrodes 104, so that the morphology of the organic
semiconductor single crystal array keeps basically unchanged before
crossing the electrodes 100, at the electrode edges 101 and 103, on
the electrodes 102, and after crossing the electrode 104. Compared
with transferring pre-grown organic semiconductor single crystals
on source/drain electrodes as reported in the prior art, the
in-situ growth of organic semiconductor single crystal array which
crossing the electrodes has avoided the damage to organic
semiconductor single crystals during transferring and the poor
contact issue between the electrodes and organic semiconductor
single crystals after transferring. The possibility of preparing an
organic semiconductor single crystal array with sufficiently high
effective coverage ratio or even complete/full coverage is greatly
improved.
[0057] The second object of the present invention is to provide a
field-effect transistor, the field-effect transistor comprises any
form of organic single-crystalline semiconductor structure as
described above. The field-effect transistor includes top-gate and
bottom-gate devices. The gate and dielectric layer of the top-gate
devices are located above the organic single-crystalline
semiconductor structure. The gate and dielectric layer of the
bottom-gate devices are located beneath the organic
single-crystalline semiconductor structure.
[0058] In the field-effect transistor, when the voltage is applied,
the electrodes in the organic single-crystalline semiconductor
structure aforementioned can be divided into source electrodes and
drain electrodes according to whether they are grounded or not. The
source, drain and gate electrodes in the field-effect transistor
are commonly used electrodes in semiconductor devices; the
electrodes can be selected from metal or non-metal; the electrodes
can be selected from the same kind or different kinds of
metal/non-metal stacking together; preferably, the metal electrodes
can be selected from platinum (Pt), gold (Au), silver (Ag),
aluminum (Al), copper (Cu), calcium (Ca), chromium (Cr), the
non-metal electrodes can be selected from silicon, graphene and its
derivatives. Preferably, for p-type semiconductors, the
source/drain electrodes are selected from metals whose work
function differs from the HOMO energy level of the corresponding
semiconductor layer by .ltoreq.0.5 eV, which is helpful to reduce
the injection barrier, improve the transport performance of
carriers, and reduce the threshold voltage as well as sub-threshold
slope. More preferably, the source/drain electrodes are selected
from metals with high affinity for the organic semiconductor layers
and/or organic solvents. It helps to spread the organic solutions
on the substrate for the solution-processed organic semiconductor
layer. Here, the arrangement of organic molecules at the gas-liquid
interface is easier to control, and it benefits the adsorption of
organic semiconductor molecules on the metal electrodes to form a
well-aligned organic semiconductor single crystal array.
[0059] The thickness of the source/drain electrodes is 0.1 nm to
100 nm; preferably, the thickness of the source/drain electrodes is
10 nm to 50 nm. If the source/drain electrodes are too thin,
contact problems might occur for devices in TGBC structure, as a
result, the transport performance of carrier decreases and the
required turn-on voltage increases. If the source/drain electrodes
are too thick, it will hinder the growth of crystals on the
substrate with pre-deposited source/drain electrodes, which may
result in discontinuity of the crystal arrays, deterioration of the
crystal quality, and easy breakage of crystals, additionally, the
processing costs are increased.
[0060] The type and thickness of the gate electrodes can be
adjusted according to actual condition. The thickness of gate
electrodes cannot be too thin, otherwise the surface of gate
electrodes is easily damaged. Moreover, the dielectric layer (the
gate insulating layer) of the devices in TGBC structure has certain
roughness and undulations, which will result in failure for
conducting of electrodes. In addition, in order to save production
cycle and raw materials, the dielectric layer should not be too
thick. The thickness of the dielectric layer is 10 nm to 100 nm.
Preferably, the thickness of the dielectric layer is 20 nm to 50
nm.
[0061] The dielectric layer is an organic or inorganic molecular
layer with dielectric properties; preferably, it can be selected
from any one or more of polymethyl methacrylate, polyvinyl alcohol,
polyvinyl acetate, polyimide, polyvinylidene fluoride,
polyvinylidene fluoride copolymer, polyvinylidene
fluoride-trifluoroethylene-chlorofluoroethylene, polystyrene,
poly-.alpha.-methylstyrene, polyvinylpyrrolidone, polyvinylphenol,
parylene, benzocyclobutene, perfluoro(1-butenyl vinyl ether)
polymer and cyanoethyl propane stacking/overlapping together. In
order to reduce the process steps and equipment cost, the selected
dielectric layer can be prepared by a solution method, which has
good solubility in an orthogonal solvent that does not dissolve the
organic single-crystalline semiconductor layer.
[0062] It should be noted that in order to protect the organic
single-crystalline semiconductor layer from damage during the
preparation of the dielectric layer, the lamination of dielectric
layer can be adopted. Thus, the first step is to prepare a thin
insulating layer on the organic semiconductor single crystals as
the first insulating layer for encapsulation/packaging to protect
the crystals, then a thicker insulating layer could be deposited on
the first insulating layer as the second insulating layer to
realize the switching performance of organic field-effect
transistors. The first insulating layer and the second insulating
layer can be selected from different organic molecules with
dielectric properties. Preferably, the thickness of the first
insulating layer is 2 nm to 20 nm
[0063] The substrate of the field-effect transistor is selected
from silicon substrates, metal oxide substrates, glass substrates,
ceramic substrates, or commonly used organic flexible substrates;
preferably, the organic flexible substrate could be selected from
polyethylene naphthalate, polyethylene terephthalate, polyether
ether ketone, polyimide, polycarbonate, polyether sulfone resin,
polyarylene, and polycyclic olefin.
[0064] In some embodiments, the field-effect transistor also
includes a buffer layer and/or an encapsulation layer.
[0065] The buffer layer includes various organic or inorganic thin
films that improve the efficiency of injecting carriers from the
electrodes into the semiconductor layer, which could modify the
work function or surface energy of the electrode surface, thus the
injection barrier and contact resistance could be effectively
reduce. Moreover, the performance of carrier transportation in the
devices could be improved, and the operating voltage is reduced.
The modification of the source/drain electrodes can also improve
the morphology of the organic semiconductor single crystal arrays
on the electrode surface. Optional materials of buffer layer
include transition metal oxides, metal halides, metal
phthalocyanines, aromatic sulfur compounds, self-assembled
auxiliary growth layers,
2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone,
and conjugated polyelectrolyte.
[0066] The encapsulation layer includes various organic and
inorganic thin films, which can block the active layer in the
devices by oxygen, moisture or other impurities in the environment.
To prevent the device's performance from aging too fast, the
encapsulation layer is helpful for the device to work properly in a
complex atmosphere. The optional materials of encapsulation layer
include resin, high molecular polymer, and inorganic oxide and so
on.
[0067] The third object of the present invention is to provide an
optoelectronic device. The optoelectronic device includes the
field-effect transistor above-mentioned. Preferably, the
optoelectronic device is selected from the group consisting of
light-emitting diodes, complementary circuits, displays, sensors,
and memory devices.
[0068] The fourth object of the present invention is to provide an
integrated optoelectronic device array. As shown in FIG. 7, the
integrated optoelectronic device array is obtained by integrating
one or more optoelectronic devices as described above in N
dimensions, where N is a positive integer greater than or equal to
1. The integrated array of optoelectronic devices can be widely
used in detectors, inverters, oscillators, and backplane circuitry
of organic light-emitting diode displays and so on.
[0069] The fifth object of the present invention is to provide a
method for preparing an organic single-crystalline semiconductor
structure, which includes the following steps:
[0070] 1) The growth-assistant layer and the electrodes are
sequentially prepared on the substrate; preferably, the electrodes
are in contact with the growth-assistant layer in an upper type
and/or embedded type. The upper type means that the upper surface
of the growth-assistant layer is in contact with the lower surface
of the electrodes, and the embedded type means that the electrode
is half-embed or penetrates the growth-assistant layer;
[0071] 2) The organic semiconductor material is dissolved in an
organic solvent to prepare an organic semiconductor solution;
[0072] 3) Regulate the temperature and humidity of the growth
environment to obtain a stable growth environment, the deviation of
the ambient temperature is .ltoreq..+-.2.degree. C., and the
deviation of the ambient humidity is .ltoreq..+-.3%; preferably,
the ambient temperature is 20.degree. C. to 25.degree. C.;
preferably, the ambient humidity is .ltoreq.55%; and more
preferably, the ambient humidity is .ltoreq.40%;
[0073] 4) Adjust the gap distance between the shearing tool and the
substrate that prepared in step (1), the gap distance is 50 .mu.m
to 300 .mu.m; Preferably, the gap distance is 100 .mu.m to 150
.mu.m; besides, the deviation of the gap distance that between the
lower surface of the shearing tool and the substrate .ltoreq.10
.mu.m needs to be guaranteed, in order to obtain a stable storage
space for solution. The solution storage space is the space formed
between the lower surface of the shearing tool and the substrate.
Preferably, the lower surface of the shearing tool is substantially
parallel to the substrate;
[0074] 5) The organic semiconductor solution prepared in step (2)
is filled into the solution storage space prepared in step (4), and
let it stand for 1 second to 30 seconds after the filling is
completed;
[0075] 6) Shear the organic semiconductor solution at a constant
linear velocity under a constant shearing temperature in a constant
direction from 100 to 104 to achieve organic single-crystalline
semiconductor thin film on the substrates, wherein 100 represents
before crossing the electrodes 104 represents after crossing the
electrodes; the organic single-crystalline semiconductor thin film
is composed of organic semiconductor single crystal arrays, and the
morphology of organic semiconductor single crystal array keeps
basically unchanged before crossing the electrode 100, at the
electrode edges 101 and 103, on the electrode 102, and after
crossing the electrode 104; the constant shearing temperature
refers to the temperature deviation .ltoreq..+-.1.degree. C. in the
space including the substrate and the solution storage space; the
constant linear velocity refers to the deviation of the linear
velocity .ltoreq..+-.20 .mu.m/s.
[0076] In some embodiments, the linear velocity is 1 .mu.m/s to
lcm/s; preferably, the linear velocity is 10 .mu.m/s to 2 mm/s;
more preferably, the linear velocity is 50 .mu.m/s to 1 mm/s.
[0077] In some embodiments, the shearing temperature is 0.degree.
C. to 200.degree. C.; preferably, the shearing temperature is
20.degree. C. to 150.degree. C.; more preferably, the shearing
temperature is 30.degree. C. to 100.degree. C.
[0078] Since the growth of organic single crystals is extremely
difficult to control, it is even more difficult to achieve uniform
growth crossing the electrodes and complete/full coverage on
substrates of arbitrary shape or arbitrary size. Organic
single-crystalline semiconductor thin films with aforementioned
morphology could only be obtained by combining the modification of
organic semiconductor molecules from growth-assistant layer with
careful control and integration on the growth conditions. The
growth conditions include ambient temperature, ambient humidity,
the gap distance between the shearing tool and the substrate, the
standing nucleation time, whether it is completely filled, the
shearing linear velocity and the shearing temperature.
[0079] In the step (1), the method for preparing the
growth-assistant layer can be selected from the solution casting,
spin-coating, solution shearing, solution dipping, and vapor phase
self-assembly and so on. When solution method is adopted for
preparing the growth-assistant layer, preferably, spin coating
method is adopted, the surface roughness can be controlled by
selecting suitable organic solvents and preparation temperature,
and the hydrophilicity and hydrophobicity can also be tailored
through surface treatment. The thickness and surface roughness of
the deposited source/drain electrodes can be manipulated by
evaporation rate and evaporation time. The electrodes in contact
with the growth-assistant layer in an upper type can be realized by
depositing the growth-assistant layer before the electrodes. By
partially etching the growth-assistant layer using ultraviolet
ozone/laser/plasma or other methods after depositing it and then
depositing the electrodes in etched pits, the electrodes in contact
with the growth-assistant layer in an embedded type can be
achieved. When the growth-assistant layer is located above the
electrodes, it will separate the organic semiconductor layer from
the electrodes, so that carriers cannot be directly injected into
the organic semiconductor layer from the electrodes because of the
hindrance from the growth-assistant layer, resulting in device
failure. Therefore, the location relationship that the
growth-assistant layer beneath the electrodes or with the
electrodes embedded can ensure the uniform growth of organic
single-crystalline semiconductor thin film across the electrodes
while maintaining the integrity of the organic semiconductor device
function.
[0080] In the step (1), when preparing organic solutions, it is
necessary to consider the effect on solvent evaporation rate.
Preferably, an organic solvent with a higher boiling point and a
.pi.-conjugated structure is used to prepare the organic solution;
as the most preferred, benzene solvents such as toluene, xylene,
trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene,
decalin, tetrahydronaphthalene, and chlorinated naphthalene can be
chosen for controlling the evaporation rate of the solution during
the preparation of the organic single-crystalline semiconductor
layer, therefore the control of the crystal morphology could be
achieved. Multiple solvents could also be mixed to prepare the
solution, so as to achieve more precise control over the polarity
and evaporation rate of the solution. Organic semiconductor
molecules need to be fully dissolved in organic solvents, for
example, the organic semiconductor molecules can be sufficiently
diffused and evenly distributed in the entire organic semiconductor
solution by stirring overnight on a hot stage at 50.degree. C.
Insufficient dissolution will lead to too many heterogeneous
nucleation sites, which will result in too small size of crystal
grains, thereby the uniform growth of crystals crossing the
electrodes cannot be achieved. On the other hand, the residue of
solute aggregates is likely to be enclosed by the crystal during
the crystal growth process, leading to non-uniform crystal
morphology, and reducing the electrical performance of the obtained
devices.
[0081] In order to obtain a stable growth environment, it is
necessary to precisely control the ambient humidity and ambient
temperature of the growth environment. Excessive humidity usually
causes water molecules to be adsorbed on the surface of the
growth-assistant layer and the electrodes. One result is to reduce
the control of the growth-assistant layer on organic semiconductor
molecules, because the growth interface is located on the surface
of the growth-assistant layer and the electrodes. After completing
the crystal growth, the growth interface is covered by the
crystals, thereby it is difficult to remove the moisture. The
second result is that the moisture acts as the trap for the
electron transport of organic semiconductors, which greatly reduces
the performance of electron transport in the devices, and even
causes the deactivation of devices. Third, higher humidity affects
the stability of the organic semiconductors. The ambient
temperature of the growth environment will impact the evaporation
rate of the organic solvents for the semiconductors as well as the
gradient diffusion of solute concentration during the shearing
process. Due to the organic single-crystalline semiconductor thin
films obtained having a difference in thermal expansion coefficient
with the substrate, too high or too low ambient temperature is
prone to cause cracks in the organic semiconductor thin films.
[0082] The gap distance between the shearing tool and the substrate
influences the amount of solution storage in it, and also affects
the evaporation of the solution. If the gap distance is too large,
the area of solution storage space exposed to the air will be so
large that too fast solvent evaporation will be caused, thereby the
greatly increased the crystallization rate might lead to disordered
alignment/orientation of crystals during the growth process. On the
other hand, less effective shearing from the shearing tool will
occur at the bottom of the solution if the gap distance is too
large. However, too small the gap distance will result in small
solution storage space, thus enough solution cannot be stored,
which destroys the continuity of the organic single-crystalline
semiconductor thin film, eventually, the complete/full coverage is
failed to achieve. Besides, the limit of solution storage space at
the direction perpendicular to the substrate will lead to vertical
spatial confinement. Here, the space for transforming from
metastable polymorphs to equilibrium polymorphs is not enough,
therefore, metastable polymorphs are presented in the organic
single-crystalline semiconductor thin film, and the overall quality
of thin films is damaged. The gap distance between the shearing
tool and the substrate should be equal everywhere to ensure that
the lower surface of the shearing tool is almost parallel to the
substrate. If gap distance varies between the lower surface of
shearing tool and the substrate (along the direction which is
perpendicular to the shearing direction), the droplets in the
solution storage area are likely to tilt toward the lower end due
to the gravity, so that only partial substrate can be coated with
the organic semiconductor solution. It is detrimental for attaining
complete/full coverage of organic single-crystalline semiconductor
thin films. Therefore, a suitable and constant gap distance is a
prerequisite for achieving high-quality organic single-crystalline
semiconductor thin films.
[0083] The organic semiconductor solution needs to slowly fill the
entire solution storage space, the purpose is to ensure that the
organic semiconductor solution can be effectively sheared by the
shearing tool. Thus, the highly uniform morphology and thickness of
the obtained organic single-crystalline semiconductor thin film
could be guaranteed. When the filling speed is too fast, the
droplets are easy to remain on the surface of the shearing tool,
thus disturbance to the solution in the solution storage space
might appear.
[0084] Making the organic semiconductor solution stand for a period
in the solution storage space could lead to slow evaporation of
partial solvents, a tiny amount of crystal nuclei will be formed,
which is beneficial to continuous growth of p1D or p2D morphology
for crystals initiating from the nucleation sites. The specific
time of the standing can be manipulated according to the type of
organic semiconductor molecules and the boiling point of the
selected organic solvents.
[0085] The shearing needs to be carried out along a constant
direction with a constant linear velocity and a constant shearing
temperature. Also, the process of solution shearing needs to be
performed within a suitable and constant shearing temperature
range. The constant shearing temperature is to maintain the
stability of the shearing temperature. The instability of shearing
temperature will lead to disorder in the solution during the
shearing process, and discontinuity and morphology change will
appear in the thin films. The conditions of the shearing
temperature could be adjusted according to the situations, since
the shearing temperature is required to enable the shearing rate of
the shearing tool to match the nucleation rate of the crystals. If
the shearing temperature is too low, the solvent evaporation will
be too slow during the shearing process, it does not only hinder
the alignment of the single crystals obtained, but also reduce the
effective charge transport in organic single-crystalline
semiconductor layer. Too high shearing temperature will cause too
fast solvent evaporation, thus the organic semiconductor molecules
might remain for too long in the solution storage space formed
between the underside of the shearing tool and the substrate,
leading to discontinuity of the single crystals. At the same time,
excessively high shearing temperature will implement cracks or
other damages to the crystal film, which will reduce the
performance of the devices. Constant linear velocity and shear
direction could help to better control the growth orientation for
organic semiconductor single crystals as well as morphology of the
film. Constant orientation is applied on solution, which can
achieve complete/full coverage of organic single-crystalline
semiconductor thin films on a substrate of arbitrary shape or
arbitrary size. Simultaneously, it can also realize unrestricted
in-situ continuous growth of organic single-crystalline
semiconductor thin films on a substrate of arbitrary shape or
arbitrary size. That is, when the solution supply is sufficient, it
is expected to obtain a continuous and uninterrupted growth of
completely/fully covered organic single-crystalline semiconductor
thin films. The relative linear velocity between the shearing tool
and the substrate needs to be kept constant during the solution
shearing process, in order to avoid the influence of fluctuations
caused by the instability of the linear velocity on the morphology
and quality of the crystal growth. Too low linear velocity leads to
insufficient shearing effect on the solution, therefore, the
crystal morphology cannot be well controlled, and disorderly
alignment/orientation of crystals is prone to occur. If the linear
velocity is too fast, the shearing effect on the solution will be
too strong, as a result, excessively thin crystals will be obtained
as well as increased roughness of crystal surface, ultimately, the
decreased crystal quality hampers the normal operation of the
devices.
[0086] The method for preparing organic single-crystalline
semiconductor structure as described above has a low production
cost and easiness to realize large-scale production, it is also
convenient for combing with flexibility. Unexpected effects can be
made using this method combined with the growth-assistant layer.
With the solvent evaporation of the organic semiconductor solution,
the solutes precipitate out, organic semiconductor molecules can
realize well-aligned growth crossing the electrodes along the
direction from 100 to 104 to under shearing force. The crystals are
more inclined to precipitate at the contact interface between the
organic semiconductor solution and the air due to the
growth-assistant layer. The organic semiconductor molecules have
received assistances from two directions. One is the interaction
between the growth-assistant layer and organic semiconductor
molecules and solvent molecules in the direction perpendicular to
the growth interface, and the other is the shearing force of
organic semiconductor molecules along the direction of crystal
growth. The integration of two assistances aforementioned enables
the organic single-crystalline semiconductor thin films to achieve
uniform growth crossing the electrodes. In addition, this
preparation method provides a uniform storage space for the organic
semiconductor solution, and the preparation of organic
semiconductor single-crystalline thin films which are fully covered
on a substrate of arbitrary shape or arbitrary size can be achieved
only using a very low volume of solution. With continuous supply of
the solution, unrestricted in-situ growth of organic
single-crystalline semiconductor thin films can be realized.
[0087] In some embodiments, the method for preparing the organic
single-crystalline semiconductor structure also includes the step
of further treatment for the organic single-crystalline
semiconductor thin films after step (6); preferably, the further
treatment is selected from any one or more of annealing, vacuum
treatment, solvent annealing treatment, or surface treatment. And
the surface treatment aforementioned is selected from any one or
more of ultraviolet ozone treatment, plasma treatment, infrared
light treatment, or laser etching.
[0088] For example, as for the annealing treatment, the obtained
organic single-crystalline semiconductor thin film is placed on a
hot stage, and the residual solvent molecules are removed by
annealing treatment under a certain temperature for a certain
time.
[0089] The further treatment could alter the molecular arrangement
and molecular ordering in the crystals, thereby the crystal form
could be changed, in some cases the quality of the obtained crystal
could be improved, and the patterning of the organic
single-crystalline semiconductor thin film is able to be
realized.
[0090] The method for preparing the field-effect transistors
further includes the steps of preparing gate electrodes and gate
insulating layer in the method above-mentioned for preparing the
organic single-crystalline semiconductor structures.
[0091] In some embodiments, the application of the organic
single-crystalline semiconductor structures, the organic
single-crystalline field-effect transistors, the optoelectronic
devices, and the integrated arrays of optoelectronic devices in the
fields of semiconductor devices, transportation logistics, mining,
metallurgy, environment, medical equipment, explosion-proof
testing, food, water treatment, pharmaceuticals, and
biologicals.
[0092] The beneficial effects of the present disclosure are:
[0093] 1) For the first time, an organic single-crystalline
semiconductor thin film with uniform growth morphology crossing the
electrodes is prepared by the present disclosure on the growth
interface in bottom contact structure;
[0094] 2) The effective coverage ratio of the organic
single-crystalline semiconductor thin film is improved, while
achieving high effective coverage ratio in both the lengthwise
direction and the vertical direction, thereby the channels for
carrier transport with maximized area are realized and the
requirements of high-performance devices are satisfied;
[0095] 3) The in-situ preparation of organic single-crystalline
semiconductor thin films with as complete/full coverage as possible
on bottom contact substrates of arbitrary shape or arbitrary size
is realized, which overcomes the technical bias that
completely/fully covered organic single-crystalline semiconductor
thin films cannot be produced on bottom contact structure in
theory;
[0096] 4) A uniformly grown organic semiconductor
single-crystalline thin film with complete/full coverage is
obtained at the growth interface of the bottom contact structure.
It combines the uniform growth, high effective coverage of the
morphology and the single-crystalline state of the materials
simultaneously, which satisfies the requirements for ideal
devices;
[0097] 5) A method that can realize industrialization and
large-scale production is applied, and the growth of organic
semiconductor single crystals is under control, eventually the
organic single-crystalline semiconductor thin films with precisely
controlled morphology are attained. Furthermore, the obtained
organic semiconductor devices are able to achieve high-performance
charge transport of carriers under normal operating voltage;
[0098] 6) Unrestricted in-situ growth of organic single-crystalline
semiconductor thin films is realized on bottom contact substrates
of arbitrary shape or arbitrary size.
[0099] Currently, for organic semiconductor devices, obtaining the
most ideal morphology of material (i.e., achieving an organic
single-crystalline semiconductor thin film with the effective
coverage ratio as large as possible and a uniformly grown
morphology on a bottom contact substrate of arbitrary shape or
arbitrary size) on the bottom contact structure is the biggest
bottleneck for higher performance. The preparation method provided
by the present invention overcomes technical bias and turns the
preparation of ideal semiconductor devices into reality. The
organic single-crystalline semiconductor thin films based on the
method provided by the present invention have well-defined
morphology, highly uniform thickness, as well as uniform
alignment/orientation. And the thin films can grow uniformly
crossing the electrodes, achieving complete/full coverage on bottom
contact substrates of arbitrary shape or arbitrary size. The
in-situ unrestricted growth can be realized, which is facile to
produce on a large scale, and the prepared semiconductor devices
are easy to integrate, which is beneficial for the realizing the
industrialization.
BRIEF DESCRIPTION OF THE DRAWINGS
[0100] FIG. 1A-FIG. 1C are a schematic diagram of the structure of
a commonly used organic field-effect transistor device, FIG. 1A is
the BGTC type, FIG. 1B is the bottom gate-bottom contact type, and
FIG. 1C is the TGBC type.
[0101] FIG. 2 is a schematic diagram of working principles of the
carrier injection and extraction for coplanar and staggered device
structures. Gate dielectric is the gate insulating layer. CAZ
refers to the carrier accumulation zone.
[0102] FIG. 3 is a schematic diagram of the resistance in a BGTC
device and a TGBC structure device.
[0103] FIG. 4A-FIG. 4C are a schematic diagram of the organic
single-crystalline semiconductor structure and the contact type of
the growth-assistant layer and the electrodes of the present
invention. FIG. 4A represents the upper type, FIG. 4B represents
the half-embedding or penetrating in the embedded type, and FIG. 4C
represents an organic single-crystalline semiconductor
structure.
[0104] FIG. 5 is a schematic diagram of the array with linear-type
arrangement of the present invention and a stereogram of an organic
single-crystalline linear element, where a is the width of the
linear element, b is the thickness of the linear element, c is the
length of the linear element, and g is the width of the gap between
the linear elements, c.sub.L1, c.sub.L2, . . . , c.sub.Lm represent
continuous lengths of crystals c.sub.L in the 1, 2, . . . , m
channels in m adjacent and continuous channels, respectively. And
represent the contact widths k between the 1, 2, . . . , n crystals
and source/drain electrodes, respectively, W represents width of
channel, A represents the orientation angle.
[0105] FIG. 6 is a schematic diagram of the structure of the
organic single-crystalline field-effect transistor of the present
invention.
[0106] FIG. 7 is a schematic diagram of the effect of the
integrated array of optoelectronic devices of the present
invention.
[0107] FIG. 8 is an optical microscope image of the organic
single-crystalline semiconductor structure of Example 1.
[0108] FIG. 9A is a schematic diagram of corresponding to the
optical microscope image in FIG. 8, and FIG. 9B is a partial
enlarged view within the dashed frame in FIG. 9A, which is a
schematic diagram of uniform growth crossing the electrodes, FIG.
9C--FIG. 9H is a schematic diagram of non-uniform growth, where the
organic single-crystalline semiconductor thin film grows crossing
the electrodes along the crystal growth direction, 100 represents
the area before crossing the electrode, 101 and 103 represent the
area at the edges of the electrode, 102 represents the area on the
electrode, 104 represents the area after crossing the electrode,
and the area on the electrode refers to the area covered by the
organic single-crystalline semiconductor thin films on the
electrode.
[0109] FIGS. 10A-10F are cross-polarized optical microscope images
showing the morphology change of the organic semiconductor
single-crystalline thin films crossing the electrodes.
[0110] FIG. 11 is a cross-polarized optical microscope image of the
organic single-crystalline semiconductor structure in Example
1.
[0111] FIG. 12 is an atomic force microscope image and
corresponding height data analysis of the organic
single-crystalline semiconductor structure in Example 1.
[0112] FIG. 13 is an optical microscope image of the organic
single-crystalline semiconductor structure in Example 7.
[0113] FIG. 14 is an optical microscope image of the organic
single-crystalline semiconductor structure in Comparative Example
1.
[0114] FIG. 15 is the typical transfer characteristics of several
organic single-crystalline field-effect transistors in Example 4
under the operating voltage of V.sub.DS=-60V, V.sub.G=-60V, wherein
V.sub.DS is the source-drain voltage, and V.sub.G is the gate
voltage;
[0115] FIG. 16 is the typical transfer characteristics of several
organic single-crystalline field-effect transistors in Example 7
under the operating voltage of V.sub.DS=-60V, V.sub.G=-60V.
[0116] FIG. 17 is an optical microscope image of the organic
single-crystalline semiconductor structure in Comparative Example
2.
[0117] FIG. 18 is a schematic structural diagram of an organic
single-crystalline field-effect transistor in Comparative Example
3.
[0118] FIG. 19 is the typical transfer characteristics of several
organic single-crystalline field-effect transistors in Comparative
Example 3 under the operating voltage of V.sub.DS=-60V,
V.sub.G=-60V.
[0119] FIG. 20 is an optical microscope image of the organic
single-crystalline semiconductor structure in Comparative Example
4.
[0120] FIG. 21 is an optical microscope image of the organic
single-crystalline semiconductor structure in Comparative Example
5.
[0121] FIGS. 22A-22B are schematic diagrams of prior art,
corresponding to FIG. 2 (d) and FIG. 4 (a) in W. Deng, W. Hu, and X
Zhang, Materials Today, 24, 17 (2019), respectively.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0122] The present disclosure is further described below with
reference to the drawings and embodiments. It should be noted that
the following embodiments are used to illustrate the present
invention but not to limit the scope of the present invention. In
addition, it should be understood that after reading the teachings
of the present invention, those skilled in the art can make various
changes or modifications to the present invention, and these
equivalent forms also fall within the scope defined by the appended
claims of this application.
[0123] The terms "upper", "lower", "left", "right", "vertical",
"parallel", "inner", "outer", "before", "after", etc. indicate that
the orientation or positional relationship is based on the
orientation or positional relationship shown in the attached
figures, and is only for the convenience of describing the present
invention and simplifying the description, rather than indicating
or implying that the pointed device or element must have a specific
orientation/positional relationship or be constructed/operated in a
specific direction/position, therefore, it cannot be understood as
a limitation of the present invention.
[0124] As shown in FIG. 1, an organic single-crystalline
semiconductor structure is provided in the present invention, the
structure comprises substrate, growth-assistant layer, electrodes
and organic single-crystalline semiconductor layer. The last three
are deposited sequentially from bottom to top on the substrate. The
organic single-crystalline semiconductor layer aforementioned is
grown on the growth-assistant layer and electrodes and is also in
contact with them. The organic single-crystalline semiconductor
layer is an in-situ uniformly grown organic semiconductor
single-crystalline thin film crossing the electrodes, as shown in
FIG. 8 and FIG. 9A-9B, and no obvious difference could be
distinguished by the naked eye in the optical microscope image of
the above-mentioned area. As shown in FIG. 5, FIG. 8, FIG. 9A-9B
and FIG. 11, the organic single-crystalline semiconductor layer is
organic single crystal arrays of small molecules with linear-type
arrangement/orientation that can realize uniform growth crossing
the electrodes. As displayed in FIG. 4, the growth-assistant layer
is located underneath the electrodes, the electrodes are in contact
with growth-assistant layer in an upper type and/or embedded type,
the upper type refers to the upper surface of growth-assistant
layer in contact with the lower surface of the electrodes, and the
embedded type refers to the electrodes half-embedding or
penetrating the growth-assistant layer. The electrodes are arranged
on growth-assistant layer in either or both of the upper type and
the embedded type.
[0125] In various embodiments, the organic semiconductor
single-crystalline thin film is an organic semiconductor single
crystal array composed of multiple crystals. For the description in
this article, each separate and independent crystal in the organic
semiconductor single-crystalline thin film is termed as linear
element if it meets the following two characteristics
simultaneously: 1) It can achieve uniform growth with basically
unchanged morphology crossing the electrodes, as shown in FIG. 5,
FIG. 8 and FIG. 9A-9B, wherein the black solid stripes represent
crystals. That is, the morphology of the crystal keeps unchanged
before crossing the electrode 100, at the electrode edges 101 and
103, on the electrode 102 and after crossing the electrode 104; 2)
each crystal is single crystal. Preferably, the morphology of the
linear element is pseudo 1D (p1D) or pseudo 2D (p2D), and the
thickness is highly uniform. As shown in FIG. 5, when multiple
linear elements are aligned in the same orientation along the
growth direction of the crystal, it is called linear-type
arrangement.
[0126] As shown in FIG. 6, on the basis of the above-mentioned
organic single-crystalline semiconductor structure, the present
invention also provides an organic single-crystalline field-effect
transistor with a TGBC structure, containing the above-mentioned
organic single-crystalline semiconductor structure, dielectric
layer, and gate electrodes, and the last two parts are sequentially
deposited on the surface of the organic single-crystalline
semiconductor structure. As shown in FIG. 7, the optoelectronic
device proposed by the present invention can also be integrated in
one or more dimensions to obtain an integrated array of
optoelectronic devices. The integrated array of optoelectronic
devices can be widely used in detectors, inverters, oscillators,
and backplane circuitry of organic light-emitting diode displays
and so on.
[0127] The organic single-crystalline thin films can be detected by
instruments that could analyze fine structures, such as optical
microscope with crossed polarizers, atomic force microscope,
scanning electron microscope, transmission electron microscope,
laser confocal Raman spectrometer, single-crystal diffractometer,
etc. The growth-assistant layer can be detected by instruments that
can analyze the composition of elements, such as scanning electron
microscope, transmission electron microscope, laser confocal Raman
spectrometer, X-ray diffractometer, infrared spectrometer and so
on. The structure of semiconductor devices can be inspected by
optical microscope, atomic force microscope, scanning electron
microscope, transmission electron microscope, etc. The related
performance of semiconductor devices can be tested by instruments
that can analyze the electrical/optoelectrical performance, such as
semiconductor parameter analyzer, Hall effect testing instrument,
scanning probe microscope, ferroelectric analyzer, quantum
efficiency measurement system, transient spectrometer, solar cell
I-V tester, optoelectronic detection system, micro-fluorescence
spectrometer, spectrum analyzer, conductance measurement system and
so on.
[0128] In order to characterize the morphology of organic
single-crystalline semiconductor thin films, an optical microscope
was used for observation. To characterize the quality of the
organic single-crystalline semiconductor thin films provided by the
present invention, a field-effect transistor with bottom contact
structure was prepared based on the organic semiconductor structure
aforementioned, and its field-effect behaviors were tested with a
semiconductor parameter analyzer.
Example 1
[0129] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure, the following steps are included:
[0130] (1) Take a P-type <100> silicon wafer with a thickness
of 575 with a 300 nm-thick silicon dioxide insulating layer on the
silicon wafer, then spin-coat the crosslinked polystyrene on the
substrate to prepare a growth-assistant layer;
[0131] (2) Deposit Au electrodes in long strip shape with a
thickness of about 30 nm by thermal evaporation under high vacuum
as the source/drain electrodes on the initial film prepared in step
(1), and make the upper surface of the growth-assistant layer in
contact with the lower surface of the electrodes as an upper
type;
[0132] (3) Regulate the ambient temperature and ambient humidity of
the growth environment at 20.+-.1.degree. C. and 40.+-.2%,
respectively;
[0133] (4) Adjust the gap distance between the shearing tool and
the substrate prepared in step (1) to 150 and ensure that the gap
distance between the lower surface of the shearing tool and the
substrate is equal everywhere;
[0134] (5) Prepare 1 wt % TIPS-pentacene in mesitylene solution.
After heating and stirring the solution to dissolve the solutes
sufficiently, use a pipette tip to slowly fill the solution into
the solution storage space, and let it stand for 10 s after the
space is completely filled;
[0135] (6) Use a shearing tool to slowly and uniformly shear the
solution slowly and uniformly in a constant direction from the 100
to 104 crossing the electrodes at a linear velocity of 400.+-.5
.mu.m/s under a temperature of 60.degree. C. Subsequently, the
organic single-crystalline semiconductor layer is heat-treated at
100.degree. C. for 8 hours to remove excess solvents;
[0136] (7) Spin-coat a dielectric layer on the organic
single-crystalline semiconductor layer and deposit the gate
electrodes of Au with a thickness of about 50 nm by thermal
evaporation under a high vacuum to obtain organic
single-crystalline field-effect transistors.
[0137] The substrate can be selected from commonly used organic
semiconductor device substrates. Further, the substrate can be a
hard substrate, such as a silicon substrate (Si/SiO2), a metal
oxide substrate (AlOx) and so on. And the substrate also could be a
flexible polymer substrate, such as polyethylene terephthalate
(PET), polyethylene naphthalate (PEN), polyimide (PI) and so
on.
[0138] Use optical microscope and atomic force microscope to
extract the fine structure and morphology information to
characterize the structure and morphology of the obtained organic
single-crystalline semiconductor thin films, and the electrical
performance of field-effect transistors is characterized by
semiconductor parameter analyzer which is capable of detecting the
comprehensive electrical properties of various semiconductor
devices and materials. According to the characterization results,
the organic semiconductor single-crystalline thin films prepared in
this embodiment is grown on both the growth-assistant layer and the
electrodes. The organic single-crystalline semiconductor thin film
is composed of organic semiconductor single crystal arrays. The
morphology of organic semiconductor single crystal arrays keeps
basically unchanged before crossing the electrode 100, at the
electrode edges 101 and 103, on the electrode 102, and after
crossing the electrode 104. The corresponding organic
single-crystalline semiconductor structure satisfies the depositing
order that the growth-assistant layer, the electrodes, and the
organic single-crystalline semiconductor layer are deposited on the
substrate sequentially from bottom to top.
Example 2
[0139] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0140] For the preparation method of the field-effect transistor
device of the Example 2, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 3
[0141] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0142] For the preparation method of the field-effect transistor
device of the Example 3, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 4
[0143] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0144] For the preparation method of the field-effect transistor
device of the Example 4, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 5
[0145] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0146] For the preparation method of the field-effect transistor
device of the Example 5, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 6
[0147] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0148] For the preparation method of the field-effect transistor
device of the Example 6, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 7
[0149] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure.
[0150] For the preparation method of the field-effect transistor
device of the Example 7, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 8
[0151] A bottom contact organic single-crystalline semiconductor
structure based on Rubrene and a preparation method thereof.
[0152] For the preparation method of organic single-crystalline
semiconductor structure of the Example 8, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 9
[0153] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0154] For the preparation method of organic single-crystalline
semiconductor structure of the Example 9, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 10
[0155] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method for TGBC devices based on
the structure.
[0156] For the preparation method of the field-effect transistor
device of the Example 10, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 11
[0157] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0158] For the preparation method of organic single-crystalline
semiconductor structure of the Example 11, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 12
[0159] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method thereof.
[0160] For the preparation method of organic single-crystalline
semiconductor structure of the Example 12, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 13
[0161] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method thereof.
[0162] For the preparation method of organic single-crystalline
semiconductor structure of the Example 13, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 14
[0163] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method thereof.
[0164] For the preparation method of organic single-crystalline
semiconductor structure of the Example 14, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 15
[0165] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method thereof.
[0166] For the preparation method of organic single-crystalline
semiconductor structure of the Example 15, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 16
[0167] A bottom contact organic single-crystalline semiconductor
structure based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene
(C.sub.8-BTBT) and a preparation method thereof.
[0168] For the preparation method of organic single-crystalline
semiconductor structure of the Example 16, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 17
[0169] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0170] For the preparation method of organic single-crystalline
semiconductor structure of the Example 17, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 18
[0171] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0172] For the preparation method of organic single-crystalline
semiconductor structure of the Example 18, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 19
[0173] A bottom contact organic single-crystalline semiconductor
structure based on
2,8-difluoro-5,11-bis[2-(triethylsilyl)ethynyl]-anthradithiophen- e
(diF-TES-ADT) and a preparation method for TGBC devices based on
the structure.
[0174] For the preparation method of the field-effect transistor
device of the Example 19, refer to the Example 1, the formula and
process parameters are shown in Table 1 and Table 2, respectively.
The structure and performance characterization methods are the same
as those in Example 1. The related device performance is shown in
Table 4.
Example 20
[0175] A bottom contact organic single-crystalline semiconductor
structure based on
2,8-difluoro-5,11-bis[2-(triethylsilyl)ethynyl]-anthradithiophen- e
(diF-TES-ADT) and a preparation method thereof.
[0176] For the preparation method of organic single-crystalline
semiconductor structure of the Example 20, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 21
[0177] A bottom contact organic single-crystalline semiconductor
structure based on
2,8-difluoro-5,11-bis[2-(triethylsilyl)ethynyl]-anthradithiophen- e
(diF-TES-ADT) and a preparation method thereof.
[0178] For the preparation method of organic single-crystalline
semiconductor structure of the Example 21, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 22
[0179] A bottom contact organic single-crystalline semiconductor
structure based on Perylene and a preparation method thereof.
[0180] For the preparation method of organic single-crystalline
semiconductor structure of the Example 22, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 23
[0181] A bottom contact organic single-crystalline semiconductor
structure based on 9,10-diphenylanthracene (9,10-DPA) and a
preparation method thereof.
[0182] For the preparation method of organic single-crystalline
semiconductor structure of the Example 23, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Example 24
[0183] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0184] For the preparation method of organic single-crystalline
semiconductor structure of the Example 24, refer to the step (1-6)
in Example 1, the formula and process parameters are shown in Table
1 and Table 2, respectively. The structure characterization methods
are the same as those in Example 1.
Comparative Example 1
[0185] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure, the following steps are included:
[0186] (1) Take a PEN substrate with a thickness of 200 then
deposit Au electrodes in long strip shape with a thickness of about
30 nm by thermal evaporation under high vacuum as the source/drain
electrodes on the substrate;
[0187] (2) Regulate the ambient temperature and ambient humidity of
the growth environment at 25.+-.1.degree. C. and 50.+-.2%,
respectively;
[0188] (3) Adjust the gap distance between the shearing tool and
the substrate prepared in step (1) to 300 and ensure that the gap
distance between the lower surface of the shearing tool and the
substrate is equal everywhere;
[0189] (4) Prepare 1 wt % TIPS-pentacene in mesitylene solution.
After heating and stirring the solution to dissolve sufficiently,
use a pipette tip to slowly fill the solution into the solution
storage space, and let it stand for 10 s after it is completely
filled;
[0190] (5) Use a shearing tool to shear the solution slowly and
uniformly in a constant direction from the 100 to 104 crossing the
electrodes at a linear velocity of 400.+-.10 .mu.m/s under a
temperature of 60.degree. C. Subsequently, the organic
single-crystalline semiconductor layer is heat-treated at
100.degree. C. for 8 hours to remove excess solvents;
[0191] (6) Spin-coat a dielectric layer on the organic
single-crystalline semiconductor layer and deposit the gate
electrodes of Au with a thickness of about 50 nm by thermal
evaporation under a high vacuum to obtain organic
single-crystalline field-effect transistors.
[0192] The structure and device performance characterization method
of Comparative Example 1 are the same as those methods in Example
1.
Comparative Example 2
[0193] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method for TGBC devices based on
the structure, the following steps are included:
[0194] (1) Take a P-type <100> silicon wafer with a thickness
of 575 with a 300 nm-thick silicon dioxide insulating layer on the
silicon wafer, then spin-coat the crosslinked polystyrene on the
substrate to prepare a growth-assistant layer;
[0195] (2) Deposit Au electrodes in long strip shape with a
thickness of about 30 nm by thermal evaporation under high vacuum
as the source/drain electrodes on the initial film prepared in step
(1), and make the upper surface of the growth-assistant layer in
contact with the lower surface of the electrodes as an upper
type;
[0196] (3) Regulate the ambient temperature and ambient humidity of
the growth environment at 20.+-.1.degree. C. and 50.+-.2%,
respectively;
[0197] (4) Prepare 0.1 wt % TIPS-pentacene in mesitylene solution.
After it is fully dissolved, use the droplet-pinned crystallization
method (DPC) at a temperature of 60.degree. C. on the substrate
prepared in step (2). Subsequently, the organic single-crystalline
semiconductor layer is heat-treated at 100.degree. C. for 8 hours
to remove excess solvents;
[0198] (5) Spin-coat a dielectric layer on the organic
single-crystalline semiconductor layer and deposit the gate
electrodes of Au with a thickness of about 50 nm by thermal
evaporation under a high vacuum to obtain organic
single-crystalline field-effect transistors.
[0199] The structure and device performance characterization method
of Comparative Example 2 are the same as those methods in Example
1.
Comparative Example 3
[0200] A preparation method for BGTC devices based on
6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene), the
following steps are included:
[0201] (1) Take a P-type <100> silicon wafer with a thickness
of 575 with a 300 nm-thick silicon dioxide insulating layer on the
silicon wafer, then spin-coat the crosslinked polystyrene on the
substrate to prepare an growth-assistant layer;
[0202] (2) Regulate the ambient temperature and ambient humidity of
the growth environment at 20.+-.1.degree. C. and 50.+-.2%,
respectively;
[0203] (3) Adjust the gap distance between the shearing tool and
the substrate prepared in step (1) to 150 and ensure that the gap
distance between the lower surface of the shearing tool and the
substrate is equal everywhere;
[0204] (4) Prepare 1 wt % TIPS-pentacene in mesitylene solution.
After sufficiently dissolving the solutes in the solution, use a
shearing tool to shear the solution slowly and uniformly in a
constant direction from the 100 to 104 crossing the electrodes on
the substrate prepared in step (1) at a linear velocity of
400.+-.10 .mu.m/s under a temperature of 60.degree. C.
Subsequently, the organic single-crystalline semiconductor layer is
heat-treated at 100.degree. C. for 8 hours to remove excess
solvents;
[0205] (5) Spin-coat a dielectric layer on the organic
single-crystalline semiconductor layer and deposit the source/drain
electrodes of Au with a thickness of about 50 nm by thermal
evaporation under a high vacuum to obtain organic
single-crystalline field-effect transistors.
[0206] The structure and device performance characterization method
of Comparative Example 3 are the same as those methods in Example
1.
Comparative Example 4
[0207] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0208] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 4, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 5
[0209] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0210] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 5, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 6
[0211] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0212] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 6, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 7
[0213] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0214] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 7, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 8
[0215] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0216] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 8, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 9
[0217] A bottom contact organic single-crystalline semiconductor
structure based on 6,13-bis(triisopropylsilylethynyl) pentacene
(TIPS-pentacene) and a preparation method thereof.
[0218] For the preparation method of organic single-crystalline
semiconductor structure of the Comparative Example 9, refer to the
step (1-6) in Example 1, the formula and process parameters are
shown in Table 1 and Table 2, respectively. The structure
characterization methods are the same as those in Example 1.
Comparative Example 10
[0219] A preparation method for bottom contact devices based on
6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene), the
following steps are included:
[0220] (1) Take a P-type <100> silicon wafer with a thickness
of 575 with a 300 nm-thick silicon dioxide insulating layer on the
silicon wafer;
[0221] (2) Deposit Au electrodes in long strip shape with a
thickness of about 30 nm by thermal evaporation under high vacuum
as the source/drain electrodes on the initial film prepared in step
(1), and make the upper surface of the growth-assistant layer in
contact with the lower surface of the electrodes as an upper
type;
[0222] (3) Regulate the ambient temperature and ambient humidity of
the growth environment at 25.+-.1.degree. C. and 40.+-.2%,
respectively;
[0223] (4) Adjust the gap distance between the shearing tool and
the substrate prepared in step (1) to 250 and ensure that the gap
distance between the lower surface of the shearing tool and the
substrate is equal everywhere;
[0224] (5) Prepare 5 wt % TIPS-pentacene: PS=1:1 in mesitylene
solution. After sufficiently dissolving the solutes in the
solution, use a shearing tool to shear the solution slowly and
uniformly in a constant direction from the 100 to 104 crossing the
electrodes on the substrate prepared in step (1) at a linear
velocity of 400.+-.10 .mu.m/s under a temperature of 60.degree. C.
Subsequently, the organic semiconductor layer is heat-treated at
100.degree. C. for 8 hours to remove excess solvents.
[0225] The structure and device performance characterization method
of Comparative Example 10 are the same as those methods in Example
1 Comparative Example 11:
[0226] A preparation method for bottom contact devices based on
6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene), the
following steps are included:
[0227] (1) Prepare 1 wt % TIPS-pentacene in mesitylene solution.
After sufficiently dissolving the solutes in the solution, use
drop-casting method to deposit organic single-crystalline
semiconductor thin films on the silicon wafer;
[0228] (2) Cast a PDMS film on the organic single-crystalline
semiconductor thin film prepared in step (1), after baking it at
60.degree. C. for 2 h, let it stand for 12 h;
[0229] (3) Tear off the PDMS film, and transfer the organic
semiconductor single crystals on the PDMS film to a silicon
substrate with pre-deposited long strips of Au with a thickness of
about 30 nm as source/drain electrodes under high vacuum.
[0230] The structure and device performance characterization method
of Comparative Example 11 are the same as those methods in Example
1.
[0231] The morphology of the organic single-crystalline
semiconductor layers obtained in Examples 1-24 and Comparative
Examples 1-11 were characterized by cross-polarized optical
microscope and atomic force microscope, and the performance of the
related device was tested by a semiconductor parameter analyzer.
Optical microscopy is a simple and effective method for observing
the morphology of organic single-crystalline semiconductor thin
films. Organic single crystals are anisotropic due to the highly
ordered intrinsic structure with periodical molecular ordering.
Under the orthogonal linearly polarized light of optical
microscope, the object with anisotropy will exhibit the
birefringence behavior. When the crystal growth direction is
parallel or perpendicular to the polarization angle, the image can
be used to determine whether the crystal axis in the field of view
is highly oriented by observing whether uniform color and
light-dark changes occur. This method could be applied to confirm
the single-crystallinity (A. Yamamura et al., Science Advances, 4,
eaao5758, (2018)). In the cross-polarized optical microscopic
image, if the color or gray scale is non-uniform or the color
changes, it indicates that the obtained crystal is not a single
crystal; for example, as shown in FIG. 10B-10F, different shades of
color can be observed in the organic semiconductor layer, the color
or gray scale is non-uniform, indicating that the organic
semiconductor layer is polycrystalline. If the color or gray scale
of the crystal is basically uniform, indicating that the crystal is
single-crystalline (for example, as shown in FIG. 11, the color or
gray scale of each crystal is basically uniform, and the color or
gray scale between different crystals is also basically the same,
indicating that a typical organic single-crystalline thin film is
obtained). Table 3 shows the morphology parameters of the organic
single-crystalline semiconductor structures obtained in Examples
1-24 and Comparative Examples 2-4.
[0232] FIG. 8 and FIG. 11 are an optical microscopic image and a
cross-polarized optical microscopic image both at 50.times.
magnification of an organic single-crystalline field-effect
transistor prepared in Example 1, respectively. The arrow in FIG. 8
represents the direction of crystal growth, and the horizontal
strips in the middle part are deposited electrodes, the parts above
and below the electrodes are channels, the vertical strips along
the crystal growth direction are crystals obtained. The
ribbon-shaped single crystals of TIPS-pentacene with well-aligned
arrangement/orientation could be observed both in the channels and
on the electrodes. And each crystal is linear shape under the
observation from the top view. In the optical microscopic image of
FIG. 8 and the corresponding cross-polarized optical microscopic
image of FIG. 11, no obvious difference can be noticed in the
morphology of the crystals between the electrodes and the channels.
That is, during the in-situ growth of the crystals, the morphology
keeps unchanged before crossing the electrode 100, at the electrode
edges 101 and 103, on the electrode 102, and after crossing the
electrode 104. The schematic diagram is shown in FIG. 9A, which
displays that an organic semiconductor single-crystalline thin film
with in-situ uniform growth crossing the electrodes has been
prepared. As shown in FIG. 11, the organic semiconductor
single-crystalline thin film obtained in Example 1 shows uniform
color and brightness in the cross-polarized mode, indicating that
the aligned crystals are single-crystalline. Each discrete crystal
obtained satisfies the two requirements of the linear element,
which proves that the linear elements are obtained. The contact
angle between the growth-assistant layer and water of each example
is shown in Table 4. Example 1 selected crosslinked polystyrene as
the growth-assistant layer, which contains .pi.-conjugated
structure, and its water contact angle CA.sub.water>90.degree..
The interaction exists between this growth-assistant layer and
TIPS-pentacene due to the 5 benzene rings in the core of
TIPS-pentacene. Therefore, the impact to TIPS-pentacene crystals
from the height of the electrodes during the growth has been
greatly reduced, and the crystal does not break at the junction of
the channel and the electrode. Moreover, there is no fracture of
the TIPS-pentacene crystals to be observed at the contact area
between the channels and the electrodes. The uniform growth
crossing the electrodes lead to the crystals exhibiting no grain
boundary where they encounter the electrodes, thereby the effective
charge transport of carriers is guaranteed.
[0233] As shown in FIG. 8, the orientations of the organic
single-crystalline semiconductor thin films are consistent, the
orientation angle A formed between each crystal and the crystal
growth direction could be calculated via using softwares that can
analyze image pixels (such as Image J software, Matlab, Photoshop,
Adobe Illustrator, etc., the present invention takes Image J
software as an example). Taking 10 randomly selected crystals as an
example (1.336.degree., 3.547.degree., 1.119.degree.,
2.770.degree., 2.406.degree., 2.392.degree., 2.915.degree.,
2.840.degree., 3.925.degree., 3.195.degree.), the average
orientation angle is 2.645.degree., and the degree of orientation
F=0.997, which indicates a good orientation degree. In addition,
the color of crystals is basically uniform, indicating that the
thickness of the organic semiconductor single-crystalline thin film
is basically uniform. The width of the crystal and the size of the
gap between the crystals are basically uniform, which further shows
that the morphology of the crystals is precisely controlled under
the shearing action of the shearing tool, the linear-type
arrangement of crystals is realized on the bottom contact
electrodes. FIG. 12 is an image of the morphology of the
crystalline thin film in Example 1, which is characterized by an
atomic force microscope after being processed by a software with an
image processing function (for example, NanoScope Analysis, Matlab,
etc., the present invention takes NanoScope Analysis software as an
example), which further illustrates that the width of the crystals
in the transverse direction and the thickness in the longitudinal
direction are highly uniform (the thickness b of the crystal is
12.8 nm, 12.2 nm, 12.1 nm, 12.7 nm, 12.7 nm, 12.3 nm, 12.4 nm, 12.4
nm, the average thickness b is 12.45 nm, the standard deviation is
0.24 nm, and the coefficient of variation is
0.24/12.45*100%=1.92%). It can be deduced that the linear elements
are well-aligned, which proves that an organic single-crystalline
semiconductor thin film with linear-type arrangement is
obtained.
[0234] Additionally, the morphologies of the organic
single-crystalline semiconductor thin films obtained in Examples
2-6 and Examples 8-24 are similar to those in FIG. 8, only the
crystal thickness b and width a slightly change. FIG. 13 is a
cross-polarized optical microscopic image at 50.times.
magnification of an organic single-crystalline field-effect
transistor prepared in Example 7, the gray part is the substrate.
The consistent growth of crystals on the substrate and the
electrodes could also be observed. The crystal morphology is p1D
and crystals are in ribbon-like shape. The gaps between the
crystals are too small in the channels to be distinguished with the
naked eye. In FIG. 8, FIG. 9A-9B and FIG. 11-13, it can be observed
that the coverage area of the crystals in the channels is large
while the gap between the crystals is small. Through Image J
software analysis and calculation, the effective coverage ratio
f.sub.cr in the lengthwise direction of the organic
single-crystalline semiconductor thin film of Example 1 is 100%
(f.sub.cr=(c.sub.L1.+-.c.sub.L2+ . . . +c.sub.L5)/(L.sub.1+L.sub.2+
. . . +L.sub.5)-(101.2 .mu.m+98.7 .mu.m+99.5 .mu.m+104.1
.mu.m+108.7 .mu.m)/(101.2 .mu.m+98.7 .mu.m+99.5 .mu.m+104.1
.mu.m+108.7 .mu.m)=100%). And the effective coverage ratio f.sub.cp
in the vertical direction is 79.88% (f.sub.cp=(k.sub.1+k.sub.2+ . .
. +k.sub.46) W=(3.8 .mu.m+3.3 .mu.m+3.6 .mu.m+4.1 .mu.m+4.4
.mu.m+4.6 .mu.m+3.8 .mu.m+4.1 .mu.m+3.8 .mu.m+3.6 .mu.m+3.6
.mu.m+3.3 .mu.m+3.6 .mu.m+2.8 .mu.m+3.3 .mu.m+3.8 .mu.m+4.1
.mu.m+4.9 .mu.m+4.1 .mu.m+3.8 .mu.m+4.1 .mu.m+3.8 .mu.m+3.6
.mu.m+2.6 .mu.m+4.4 .mu.m+4.4 .mu.m+4.6 .mu.m+3.6 .mu.m+3.3
.mu.m+4.6 .mu.m+3.6 .mu.m+4.4 .mu.m+3.1 .mu.m+4.4 .mu.m+4.9
.mu.m+4.1 .mu.m+4.9 .mu.m+4.6 .mu.m+6.4 .mu.m+5.4 .mu.m+4.6
.mu.m+3.6 .mu.m+4.6 .mu.m+4.4 .mu.m+3.8 .mu.m+4.6 .mu.m)/234.2
.mu.m=79.88%). The gap g is about 0.72 .mu.m. Therefore, the
complete/full coverage of the organic single-crystalline thin film
is achieved. The width change R before and after the crystal
crossing the electrodes is <5%. The length c of the crystal is
in the order of ten millimeters, and the width a of the crystal is
several microns. Combined with the crystal thickness measured by
the atomic force microscope in FIG. 11, the thickness b of the
crystal is a dozen nanometers, obviously, c/a>500, c/b>500
can be obtained, which indicates a typical p1D morphology.
[0235] For the organic field-effect transistors prepared in
Examples 1-5, Example 7, Example 10, Example 19, and Comparative
Examples 3-4, and Comparative Examples 10-11, the gate electrode is
connected to a negative voltage, the source is grounded, and the
drain is connected to a negative voltage. The transfer
characteristics of the devices are tested under V.sub.DS=-60V,
V.sub.G=-60V, the calculated mobilities and threshold voltages in
the saturation region are shown in Table 5. The hole mobility is a
type of parameter for the carrier mobility. The higher the value of
hole mobility, the faster the charge transport, and the higher the
performance of the device. The smaller the absolute value of the
threshold voltage normally means that the contact resistance is
smaller, and the loss of operating voltage is less, ultimately, the
working mode of the device is closer to the ideal state. It can be
deduced from Table 5 that the flexible organic single-crystalline
field-effect transistor prepared in Example 7 has the highest
mobility. The linear velocity and shearing temperature in solution
shearing have a greater impact on the performance of the devices.
The organic single-crystalline field-effect transistor prepared by
the linear velocity and shearing temperature selected in Example 4
has the best performance on the inorganic substrates. Several
typical transfer curves in the organic single-crystalline
field-effect transistors prepared in Example 4 are shown in FIG.
15, exhibiting uniform performance. Several typical transfer curves
in the organic single-crystalline field-effect transistors prepared
in Example 7 are shown in FIG. 16. Both FIG. 15 and FIG. 16
illustrate that the organic single-crystalline field-effect
transistors prepared by the method of present invention have
excellent device performance.
[0236] In order to illustrate the influence of the growth-assistant
layer on the crystal morphology of the organic single-crystalline
field-effect transistor in the TGBC structure, Comparative Example
1 uses the same operation process of Example 7 to prepare a device
without the growth-assistant layer. The crystal morphology obtained
in Comparative Example 1 is shown in FIG. 14. It can be observed
that the crystal cannot grow continuously on the unmodified
substrate, the crystal morphology is irregular with branching.
Additionally, the width of the crystals is non-uniform. The
performance of related field-effect transistor is unable to
measure. It explains the necessity of the growth-assistant layer
for the growth of organic semiconductor single-crystalline thin
films in devices with the TGBC structure.
[0237] In order to illustrate the advantages of the preparation
method provided by the present invention, Comparative Example 2
uses the existing technology according to the literature (H. Li et
al., Advanced Materials, 24, 2588 (2012)) to prepare the devices by
the droplet-pinned crystallization method (DPC). The crystal
morphology is shown in FIG. 17. The degree of orientation of the
crystals decreases without external shearing force, and non-uniform
color is showed in the crystal, which elucidates that precise
control of thickness in the organic single-crystalline
semiconductor layer using the DPC method cannot be achieved.
Besides, the effective coverage ratio in the channel is greatly
reduced (approximately 50%) although the width of the crystal is
larger. The degree of orientation in crystals is also greatly
reduced, and the crystal shape is irregular with branching,
moreover, the width change |R| is very obvious (|R|=28%), and the
performance of the device based on the organic single-crystalline
semiconductor thin film is shown in Table 5, which is inferior to
Example 1. The hole mobility is only 0.34 cm.sup.2 V.sup.-1
s.sup.-1, and the threshold voltage becomes larger, showing that
irregular crystal morphology and low effective coverage ratio will
reduce the device performance.
[0238] In order to illustrate the influence of the device
structure, the same solution shearing linear velocity and shearing
temperature as in Example 2 were used to prepare a BGTC organic
single-crystalline field-effect transistor in Comparative Example
3. The device structure of Comparative Example 3 is shown in FIG.
18, and in FIG. 19 a typical transfer curve of the organic
single-crystalline field-effect transistor prepared in Comparative
Example 3 is displayed. According to the results in Table 5,
compared with Example 2, the threshold voltage is greatly
increased, which is not good for the working conditions of the
devices. It could be ascribed to the heat damage on the crystal
surface during the evaporation of source/drain electrodes. Thus,
the advantages and practicality of organic single-crystalline
semiconductor devices with TGBC structure are clearly
explained.
[0239] In order to illustrate the necessity of precise control of
various conditions in the preparation method, the same organic
semiconductor small molecules, solvents, and linear velocity and
shearing temperature in solution shearing as in Example 1 were used
in Comparative Examples 4-8. However, the obtained film morphology
is shown in FIG. 20 and FIG. 21, respectively. The uniform growth
of the organic semiconductor single-crystalline film is not
obtained, because the non-ideal control of linear velocity
stability (the linear velocity is not constant in Comparative
Example 4), ambient humidity (the ambient humidity in Comparative
Example 6 is too high), ambient temperature (the ambient
temperature in Comparative Example 7 is too high and the
temperature is not constant), the gap distance between the shearing
tool and the substrate (the gap distance in Comparative Example 8
is too large), and the standing time for nucleation (In Comparative
Examples 4-5, the standing time for nucleation is too long or too
short). As a result, the crystal growth environment has been
subject to various disturbances during the crystal growing process.
Additionally, the solution evaporation and solute deposition have
not been precisely controlled, resulting in an undesirable film
morphology. Wherein, the crystal is rugged, the crystal thickness
varies a lot, moreover, the crystal orientation is disordered, and
many grain boundaries and cracks occur in the crystalline thin
film. The performance of the semiconductor device prepared based on
the thin film of Comparative Example 4 is shown in Table 5, and the
performance is far inferior to the organic single-crystalline thin
film semiconductor devices with good morphology. However, in
Comparative Examples 5-8, no thin film was obtained at all, only a
few solute aggregates showed up, thus the related semiconductor
devices could not be produced based on these conditions.
[0240] In order to show that the growth-assistant layer needs to
choose a suitable range for water contact angle CA.sub.water, in
Comparative Example 9, a superhydrophobic material was used as the
growth-assistant layer, and its water contact angle
CA.sub.water.gtoreq.120.degree. is shown in Table 4. Since the
solution cannot be well spread on this growth-assistant layer, it
is difficult to grow the crystals, therefore the organic
semiconductor single-crystalline thin films cannot be obtained. Its
morphology is similar to that of FIG. 21, eventually the device
cannot be prepared based on this growth-assistant layer.
[0241] In Comparative Example 10, organic semiconductor devices
were obtained by blending small organic semiconductor molecules
with insulating polymers. This kind of organic semiconductor thin
film is not single-crystalline, thus the typical phenomenon under
cross-polarized light aforementioned for single crystals cannot be
observed. The performance of related device is shown in Table 5.
However, due to the phase separation, the insulating polymer
increases the contact resistance, thereby the obtained organic
semiconductor device has poor contact. The relatively poor
performance of devices based on blending mixtures further confirms
the superiority of the performance of the organic
single-crystalline semiconductor device prepared based on the
organic semiconductor single-crystalline thin films provided by the
present invention.
[0242] In Comparative Example 11, the common physical transfer
method was used to transfer the organic semiconductor
single-crystalline thin films that pre-casted on the silicon wafer
to the substrate with pre-deposited source/drain electrode.
However, crystals are obtained with imperfections, and most
crystals cannot be transferred with the integrity. Since too many
steps are involved in the transfer method, the crystals transferred
to the substrate also suffer from damage and contamination. There
are many cracks on the crystal surface when the peeling off it, and
it is impossible to obtain an organic single-crystalline
semiconductor thin film with uniform growth crossing the
electrodes, moreover, the organic single-crystalline semiconductor
thin film obtained is too small to fabricate devices with excellent
performance. As shown in Table 5, the hole mobility of the device
prepared in Comparative Example 11 is only 0.02 cm.sup.2 V.sup.-1
s.sup.-1, which decreases at least an order of magnitude compared
with the device in Example 1. The threshold voltage is -39V, and
the high absolute value of the threshold voltage proves the poor
contact between the crystals and the electrodes, which will result
in serious impact on the injection and extraction of carriers. And
during the performance characterization, it was observed that many
electrodes in the devices are completely unable to work normally,
therefore the electrical performance of some devices cannot be
obtained. Thus, the advantages of the in-situ growth of the organic
semiconductor single crystal array provided by the present
invention are further confirmed through the comparison.
[0243] Through the Comparative Examples 1-11, it can be concluded
that in order to realize the preparation of ideal organic
single-crystalline semiconductor devices, it is necessary to
achieve the in-situ uniform growth of the organic
single-crystalline semiconductor thin films crossing the electrodes
on the substrate with the bottom contact structure, that is, the
device must meet four requirements at the same time as follows: (1)
sequentially deposit growth-assistant layer, electrodes, and
organic single-crystalline semiconductor layer from bottom to top
on the substrate; (2) the organic single-crystalline semiconductor
layer is in-situ grown on the growth-assistant layer and electrodes
and is also in contact with them; (3) the organic
single-crystalline semiconductor layer is an in-situ uniformly
grown organic semiconductor single-crystalline thin film crossing
the electrodes; (4) the electrodes contact with the
growth-assistant layer with protruding outside of the
growth-assistant layer. The electrodes are in contact with the
growth-assistant layer in an upper type and/or embedded type, the
upper type refers to the upper surface of growth-assistant layer in
contact with the lower surface of the electrodes, and the embedded
type refers to the electrodes half-embedding or penetrating the
growth-assistant layer. The four conditions described are
synergistic as a whole and work together to achieve the purpose of
the present invention.
TABLE-US-00001 TABLE 1 Formulations and process parameters A of
Examples 1-24 and Comparative Examples 1-11 (substrate,
growth-assistant layer, organic semiconductor material, solvent,
shearing temperature and the linear velocity in the solution
shearing) Organic linear Growth- semi- velocity in the assistant
conductor shearing solution No. Substrate layer material Solvent
temperature shearing Example 1 SiO.sub.2 crosslinked TIPS-
mesitylene 60.degree. C. 400 .+-. 5 .mu.m/s polystyrene pentacene
Example 2 SiO.sub.2 crosslinked TIPS- mesitylene 80.degree. C. 400
.+-. 5 .mu.m/s polystyrene pentacene Example 3 SiO.sub.2
crosslinked TIPS- mesitylene 40.degree. C. 400 .+-. 5 .mu.m/s
polystyrene pentacene Example 4 SiO.sub.2 crosslinked TIPS-
mesitylene 60.degree. C. 600 .+-. 5 .mu.m/s polystyrene pentacene
Example 5 SiO.sub.2 crosslinked TIPS- mesitylene 60.degree. C. 200
.+-. 5 .mu.m/s polystyrene pentacene Example 6 SiO.sub.2
Crosslinked TIPS- mesitylene: 60.degree. C. 200 .+-. 5 .mu.m/s
polymethacrylate pentacene dodecane = 1:1 Example 7 PEN crosslinked
TIPS- mesitylene 60.degree. C. 400 .+-. 5 .mu.m/s polystyrene
pentacene Example 8 SiO.sub.2 polyimide Rubrene 1-chloro-
200.degree. C. 10 .+-. 1 .mu.m/s naphthalene Example 9 SiO.sub.2
crosslinked TIPS- chloroform 0.degree. C. 1 .+-. 0.1 .mu.m/s
polystyrene pentacene Example 10 SiO.sub.2 crosslinked C.sub.8-BTBT
toluene 100.degree. C. 10000 .+-. 20 .mu.m/s polystyrene Example 11
SiO.sub.2 polyvinyl TIPS- toluene 60.degree. C. 400 .+-. 10 .mu.m/s
alcohol pentacene Example 12 SiO.sub.2 polyvinyl- C.sub.8-BTBT
dodecane 80.degree. C. 1000 .+-. 10 .mu.m/s pyrrolidone Example 13
SiO.sub.2 hexamethyl- C.sub.8-BTBT hexane 20.degree. C. 50 .+-. 1
.mu.m/s disilazane Example 14 SiO.sub.2 octadecyl C.sub.8-BTBT
heptane 30.degree. C. 500 .+-. 10 .mu.m/s trichlorosilane Example
15 SiO.sub.2 polyimide C.sub.8-BTBT trichlorobenzene 150.degree. C.
2000 .+-. 10 .mu.m/s Example 16 SiO.sub.2 benzocyclobutene
C.sub.8-BTBT m-xylene: 60.degree. C. 1000 .+-. 10 .mu.m/s dodecane
= 2:1 Example 17 SiO.sub.2 6-phenyl- TIPS- toluene 60.degree. C.
200 .+-. 10 .mu.m/s hexyltrichlorosilane pentacene Example 18
SiO.sub.2 polyethersulfone TIPS- dodecane 80.degree. C. 800 .+-. 10
.mu.m/s pentacene Example 19 SiO.sub.2 polymer based on diF-TES-
chlorobenzene 100.degree. C. 1000 .+-. 10 .mu.m/s perfluoroalkyl
ADT vinyl ether Example 20 SiO.sub.2 1:1 blend of diF-TES- toluene
40.degree. C. 800 .+-. 10 .mu.m/s polyvinyl ADT alcohol and
polyvinylidene fluoride Example 21 SiO.sub.2 1:1 blend of diF-TES-
dodecane 80.degree. C. 950 .+-. 10 .mu.m/s polystyrene and ADT
polymethyl methacrylate Example 22 AlOx octadecyl- Perylene toluene
60.degree. C. 400 .+-. 10 .mu.m/s phosphonic acid Example 23 PI
6-phenyl- 9,10-DPA mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s
hexyltrichlorosilane is deposited on polymethyl methacrylate
Example 24 PET polyvinyl Perylene toluene:hexane = 60.degree. C.
100 .+-. 10 .mu.m/s alcohol 1:1 Comparative PEN N/A TIPS-
mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s Example 1 pentacene
Comparative SiO.sub.2 crosslinked TIPS- mesitylene 60.degree. C.
N/A Example 2 polystyrene pentacene Comparative SiO.sub.2
crosslinked TIPS- mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s
Example 3 polystyrene pentacene Comparative SiO.sub.2 crosslinked
TIPS- mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s Example 3
polystyrene pentacene Comparative SiO.sub.2 crosslinked TIPS-
mesitylene 60.degree. C. 400 .+-. 50 .mu.m/s Example 4 polystyrene
pentacene Comparative SiO.sub.2 crosslinked TIPS- mesitylene
60.degree. C. 400 .+-. 10 .mu.m/s Example 5 polystyrene pentacene
Comparative SiO.sub.2 crosslinked TIPS- mesitylene 60.degree. C.
400 .+-. 10 .mu.m/s Example 6 polystyrene pentacene Comparative
SiO.sub.2 crosslinked TIPS- mesitylene 60.degree. C. 400 .+-. 10
.mu.m/s Example 7 polystyrene pentacene Comparative SiO.sub.2
crosslinked TIPS- mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s
Example 8 polystyrene pentacene Comparative SiO.sub.2 Teflon .TM.
TIPS- mesitylene 60.degree. C. 400 .+-. 10 .mu.m/s Example 9
AF1600X (AF) pentacene Comparative SiO.sub.2 N/A TIPS- mesitylene
60.degree. C. 400 .+-. 10 .mu.m/s Example 10 pentacene Comparative
SiO.sub.2 N/A TIPS- mesitylene 40.degree. C. N/A Example 11
pentacene **The actual process parameters (including the shearing
temperature and the linear velocity in the solution shearing) are
allowed to have a deviation of .+-.2% from the parameters listed in
the table.
TABLE-US-00002 TABLE 2 Formulations and process parameters B of
Examples 1-24 and Comparative Examples 1-11 (standing time, ambient
temperature, ambient humidity, gap distance, and contact type of
electrode and growth-assistant layer) Standing Ambient Ambient Gap
Contact type of electrode and No. time temperature humidity
distance growth-assistant layer Example 1 10 s 20 .+-. 1.degree. C.
40 .+-. 2% 150 .mu.m upper type Example 2 5 s 20 .+-. 1.degree. C.
50 .+-. 2% 150 .mu.m upper type Example 3 15 s 20 .+-. 1.degree. C.
40 .+-. 2% 150 .mu.m embedded type Example 4 10 s 25 .+-. 1.degree.
C. 40 .+-. 2% 100 .mu.m embedded type Example 5 2 s 25 .+-.
1.degree. C. 40 .+-. 2% 50 .mu.m embedded type Example 6 10 s 25
.+-. 1.degree. C. 50 .+-. 2% 150 .mu.m random arrangement of upper
type and embedded type Example 7 15 s 25 .+-. 1.degree. C. 50 .+-.
2% 300 .mu.m upper type Example 8 1 s 20 .+-. 1.degree. C. 50 .+-.
2% 300 .mu.m upper type Example 9 5 s 20 .+-. 1.degree. C. 30 .+-.
2% 275 .mu.m upper type Example 10 30 s 20 .+-. 1.degree. C. 30
.+-. 2% 250 .mu.m random arrangement of upper type and embedded
type Example 11 15 s 20 .+-. 1.degree. C. 50 .+-. 2% 300 .mu.m
upper type Example 12 20 s 25 .+-. 1.degree. C. 30 .+-. 2% 250
.mu.m upper type Example 13 15 s 25 .+-. 1.degree. C. 55 .+-. 3%
100 .mu.m upper type Example 14 25 s 20 .+-. 1.degree. C. 30 .+-.
2% 150 .mu.m upper type Example 15 5 s 25 .+-. 2.degree. C. 40 .+-.
3% 300 .mu.m upper type Example 16 10 s 20 .+-. 1.degree. C. 40
.+-. 2% 50 .mu.m embedded type Example 17 10 s 20 .+-. 1.degree. C.
40 .+-. 2% 250 .mu.m upper type Example 18 10 s 20 .+-. 1.degree.
C. 40 .+-. 2% 250 .mu.m upper type Example 19 10 s 20 .+-.
1.degree. C. 40 .+-. 2% 250 .mu.m upper type Example 20 5 s 20 .+-.
1.degree. C. 40 .+-. 2% 200 .mu.m embedded type Example 21 5 s 25
.+-. 1.degree. C. 40 .+-. 2% 270 .mu.m embedded type Example 22 5 s
20 .+-. 1.degree. C. 40 .+-. 2% 200 .mu.m embedded type Example 23
10 s 20 .+-. 1.degree. C. 40 .+-. 2% 200 .mu.m embedded type
Example 24 10 s 20 .+-. 1.degree. C. 40 .+-. 2% 300 .mu.m embedded
type Comparative 15 s 25 .+-. 1.degree. C. 50 .+-. 2% 300 .mu.m
upper type Example 1 Comparative N/A 25 .+-. 1.degree. C. 50 .+-.
2% N/A upper type Example 2 Comparative 5 s 20 .+-. 1.degree. C. 50
.+-. 2% 150 .mu.m N/A Example 3 Comparative 60 s 20 .+-. 3.degree.
C. 50 .+-. 2% 200 .mu.m upper type Example 4 Comparative 0 s 25
.+-. 2.degree. C. 50 .+-. 3% 200 .mu.m upper type Example 5
Comparative 10 s 25 .+-. 2.degree. C. 80 .+-. 5% 200 .mu.m upper
type Example 6 Comparative 10 s 30 .+-. 3.degree. C. 50 .+-. 2% 200
.mu.m upper type Example 7 Comparative 10 s 25 .+-. 1.degree. C. 50
.+-. 2% 1000 .mu.m embedded type Example 8 Comparative 10 s 25 .+-.
1.degree. C. 50 .+-. 2% 250 .mu.m upper type Example 9 Comparative
5 s 25 .+-. 1.degree. C. 40 .+-. 2% 250 .mu.m upper type Example 10
Comparative N/A 25 .+-. 2.degree. C. 50 .+-. 2% N/A N/A Example 11
** The actual process parameters (including the standing time,
ambient temperature, ambient humidity, and gap distance) are
allowed to have a deviation of .+-. 2% from the parameters listed
in the table.
TABLE-US-00003 Table 3 Morphology parameters of the organic
single-crystalline semiconductor structures of Examples 1-24 and
Comparative Examples 2-4 morphology of the No. f.sub.cr f.sub.cp F
linear element b g Example 1 100% 79.88% 0.997 p1D(c/a > 500,
12.45 nm .+-. 0.24 nm 0.72 .mu.m c/b > 500) Example 2 100%
64.23% 0.993 p1D (c/a > 500, 23.36 nm .+-. 0.58 nm 0.45 .mu.m
c/b > 500) Example 3 100% 73.15% 0.989 p1D (c/a > 1000, 17.10
nm .+-. 0.23 nm 0.81 .mu.m c/b > 1000) Example 4 100% 83.42%
0.830 p1D (c/a > 500, 45.76 nm .+-. 4.09 nm 3.77 .mu.m c/b >
500) Example 5 100% 69.64% 0.878 p1D (c/a > 1000, 40.68 nm .+-.
7.76 nm 6.12 .mu.m c/b > 1000) Example 6 100% 67.62% 0.851
p1D(c/a > 500, 20.37 nm .+-. 2.53 nm 4.14 .mu.m c/b > 500)
Example 7 100% 84.13% 0.986 p1D (c/a > 2000, 42.56 nm .+-. 8.20
nm 10.56 .mu.m c/b > 2000) Example 8 94.12% 54.27% 0.986 p1D
(c/a > 500, 398.21 nm .+-. 52.11 nm 14.35 .mu.m c/b > 500)
Example 9 88.50% 68.98% 0.994 p1D (c/a > 500, 201.47 nm .+-.
35.93 nm 17.88 .mu.m c/b > 500) Example 10 84.36% 73.10% 0.924
p2D (a/b > 1000, 58.17 nm .+-. 12.31 nm 11.85 .mu.m c/b >
1000) Example 11 89.35% 66.63% 0.941 p1D (c/a > 500, 47.08 nm
.+-. 9.74 nm 6.34 .mu.m c/b > 500) Example 12 97.81% 80.07%
0.950 p2D (a/b > 500, 54.86 nm .+-. 2.44 nm 7.09 .mu.m c/b >
500) Example 13 80.21% 51.36% 0.627 p2D (a/b > 500, 67.89 nm
.+-. 25.11 nm 25.80 .mu.m c/b > 500) Example 14 90.35% 82.17%
0.793 p1D (c/a > 500, 36.75 nm .+-. 6.12 nm 4.43 .mu.m c/b >
500) Example 15 83.58% 100% 1 p2D (a/b > 2000, 57.21 nm .+-.
18.64 nm 0 .mu.m c/b > 2000) Example 16 95.71% 56.90% 0.878 p1D
(c/a > 500, 2.37 nm .+-. 0.89 nm 5.32 .mu.m c/b > 500)
Example 17 92.19% 50.48% 0.913 p1D (c/a > 500, 17.21 nm .+-.
6.56 nm 12.39 .mu.m c/b > 500) Example 18 84.06% 80.12% 0.925
p1D (c/a > 500, 36.75 nm .+-. 6.12 nm 4.43 .mu.m c/b > 500)
Example 19 86.58% 79.94% 0.967 p1D (c/a > 500, 5.37 nm .+-. 2.44
nm 0.86 .mu.m c/b > 500) Example 20 99.82% 83.26% 0.948 p1D (c/a
> 500, 22.46 nm .+-. 4.85 nm 3.47 .mu.m c/b > 500) Example 21
86.58% 79.94% 0.899 p2D (a/b > 500, 17.46 nm .+-. 2.08 nm 3.90
.mu.m c/b > 500) Example 22 94.62% 51.70% 0.857 p1D (c/a >
500, 74.73 nm .+-. 15.75 nm 6.52 .mu.m c/b > 500) Example 23
100% 58.19% 0.974 p1D (c/a > 500, 9.20 nm .+-. 1.48 nm 1.15
.mu.m c/b > 500) Example 24 87.66% 50.47% 0.962 p1D (c/a >
500, 150.82 nm .+-. 35.34 nm 989.30~ c/b > 500) 995.68 .mu.m
Comparative 68.74% 44.29% 0.675 p1D (c/a > 500, 157.66 nm .+-.
62.71 nm 14.19 .mu.m Example 2 c/b > 500) Comparative 94.36%
78.68% 0.996 p1D (c/a > 500, 19.21 nm .+-. 3.84 nm 0.77 .mu.m
Example 3 c/b > 500 Comparative 73.43% 51.95% 0.571 N/A 189.52
nm .+-. 121.44 nm 4.38~ Example 4 36.72 .mu.m **Actually obtained
crystal morphology parameters (including effective coverage fcr in
the lengthwise direction, effective coverage f.sub.cp in the
vertical direction, c/a, c/b, a/b, degree of orientation F,
thickness b, and gap g) are allowed .+-.3% deviation from the
tested parameters listed in the table.
TABLE-US-00004 TABLE 4 CA.sub.water of the contact angle between
the growth-assistant layer and water in Examples 1-24 and
Comparative Examples 1-10 growth- assistant crosslinked crosslinked
layer polystyrene polymethacrylate polyimide polyvinyl alcohol
CA.sub.water ~107.degree. ~68.degree. ~80.degree. ~36.degree.
growth- polyethersulfone polymer based on 1:1 blend of 1:1 blend of
assistant perfluoroalkyl vinyl ether polyvinyl alcohol polystyrene
and layer and polyvinylidene polymethyl fluoride methacrylate
CA.sub.water ~78.degree. ~120.degree. ~70.degree. ~76.degree.
growth- hexamethyldisilazane 6-phenylhexyl octadecyl Teflon .TM.
AF1600X assistant trichlorosilane trichlorosilane (AF) layer
CA.sub.water -60.degree. ~90.degree. ~100.degree. >120.degree.
growth- polyvinylpyrrolidone octadecylphosphonic acid assistant
layer CA.sub.water ~30.degree. ~117.degree. **The actual parameter
of CA.sub.water and the tested parameters listed in the table are
allowed to have a deviation of .+-.3%.
TABLE-US-00005 TABLE 5 Performance statistics of saturation region
mobilities and threshold voltages of the organic single-crystalline
field- effect transistors at V.sub.DS = -60 V, V.sub.G = -60 V
obtained in Examples 1-5, Example 7, Example 10, Example 19 and
Comparative Examples 3-4, Comparative Examples 10-11. No. Hole
mobility Threshold voltage Example 1 0.87 cm.sup.2 V.sup.-1s.sup.-1
-9 V Example 2 0.64 cm.sup.2 V.sup.-1s.sup.-1 -10 V Example 3 0.58
cm.sup.2 V.sup.-1s.sup.-1 -16 V Example 4 1.04 cm.sup.2
V.sup.-1s.sup.-1 -12 V Example 5 0.68 cm.sup.2 V.sup.-1s.sup.-1 -5
V Example 7 1.49 cm.sup.2 V.sup.-1s.sup.-1 -11 V Example 10 0.92
cm.sup.2 V.sup.-1s.sup.-1 -15 V Example 19 0.61 cm.sup.2
V.sup.-1s.sup.-1 -10 V Comparative Example 3 0.11 cm.sup.2
V.sup.-1s.sup.-1 -36 V Comparative Example 4 0.12 cm.sup.2
V.sup.-1s.sup.-1 -30 V Comparative Example 10 0.42 cm.sup.2
V.sup.-1s.sup.-1 -27 V Comparative Example 11 0.02 cm.sup.2
V.sup.-1s.sup.-1 -39 V
* * * * *